Dragons live for ages - just what are they up to when not sleeping?

Regardless of age, kind or type of dragon they need a lairs - hopefully with treasure. Putting money into large, hidden spaces is just what they do. That 'home' may be abandoned caves, out of the way castles or great subterranean caverns - it will have loot. Then what? How does one keep the loot from getting looted? Or the dragons themselves from being turned into undragons or ex-dragons?

And why the lair in the first place? Legends and lore suggest 'immortals' (extra-planars like fae, elementals, fiends, godlings, celestials and so on), seem to live off of some kind of spiritual substance. Gods feed off of faith, hags consume suffering, demons hunger for pain, devils develop angst, angels seek radiant joy and elementals just need their own... elements. Just as life must make and eat life, so too does each kind of supernatural creature create &/or feed off of their own product-substance. Dragons live off of draconic archetypes.

Otherwise, it would stand to reason that dragons do not even need their treasure. Where would they spend it? What would they do with something like an elaborate crown that fits a creature a fraction their size - and one of a totally different shape at that? A priceless vase from another age would lack even a place to stand... let alone someone to show it to. Exotic and ancient magical plate mail for... whom exactly? All this treasure seems so pointless in the hands of a gigantic energy-lizard. One must assume it fulfills a need beyond mere decoration.

Also of interest: gathering treasure as a colossal monster would be complicated. Most of the best stuff is in cities. In 5e D&D, even a few score archers they can typically bring down any target in a few seconds. As such, the brute force method is out of the question for drakes. They need to play the long game in order to bring the risk to zero and their gold cache to the limit.

Investments: Making The Perfect Homestead

• weaponize the lair: traps (to test invaders and warn guards), breath weapon buffs, immunity manipulation (lava for fire dragons etc), electric 'wires' that appear to be floor or wall decorations
• livable & fun sanctum (enchanted chandelier permanent light, choir of magic mouths, etc)
• decorate lair
• odd collections, games & toys
• giant sized things that a giant would not want nor be able to move
• mine, harvest &/or develop treasure via servants & magic (metals, components, formulae etc)
• mercenaries to get pre-made treasure / defeat dragon slayers ('dragon slayers most often fight dragon slayers representing other dragons')
• hobbies down through the ages ('knitting!' or 'kite flying')

Weaponized Lair: When Finding The Dragon Is The Good News

Assuming a dragon can survive every risk over thousands of years, what did they do to pass the time? If you study their lore the list of possible pass times is quite short:

• collect gold coins
• sleep

That is a very short list and neither of them is particularly exciting. Remember that all ancient dragons are incredibly smart (white drakes as the exception) - how do they endure the infinite solitude?

This one is more challenging than you may think. Were a dragon alive today it would know how irksome medieval times were, what Roman centurions were like and even make fun of those silly pre-socratic philosophers. They would have been there and seen it.

They would collect exotic treasures, have draconic hobbies and habits and finally they would have some hard-core games.

Brainstorm:

Dragon treasure:

large, massive things, surprisingly fragile & tied down hard to take away - especially by giants

Dragon hobbies:

• building & testing lairs: games around 'morsels' (mortals) trying to escape with loot or hiding for long periods of time
• dragon architecture: perches, traps that only 'fit' small people

Dragon Pass-Times:

• how to find and get treasure out of well-defended cities
• how to re-find treasure (enchantment, scrying)
• games they can play with wee ones
• what to do when everyone dies from old age or other 'natural' (i.e. violent) death
• how to make treasure: getting resources and shaping the goods into gooder goods
• dealing with immortals (The Fae), semi-mortals (hags),
• playable games
• games using people as subjects, targets, ones who suffer most

Notes: dragons cast spells with no components. Reincarnation is a free spell for them! So is magic mouth. They may also cast all 'ritual' spells.

May collect magick Shopp stuff.

Toys And Trinkets:

• Odds & Ends - Dragons would have to collect things that survive their breath weapons - the acidic and fire-using dragons need to be extra careful or
• Collections: Puppets: from hobbit sized to giant sized, stamps? matching cutlery? terrible paintings?). Collection aught to resist the owner's breath weapon, example: Reds would enjoy fire-proof collections so stone sculptures are great, oil paintings less so - collecting gun-powder style fireworks would be interesting but would get annoying eventually. Greens collecting things would end up accidentally (or intentionally) adding 'spice' (i.e. horribly lethal poison) to their shared contributions. You can imagine this would change a Comicon-style event as other patrons might inexplicably die off. Blacks would often be bitter as many of their collections (even stone or glass, unknown?) tend to melt away in their magically corrosive homestead environs.
• Dragons may enjoy games pretending to have 'poor' memory (over thousands of years what do the stories look like?). May make up wild and crazy legends just to test what mortals remember of them. Will expect great sages and bards 'correct' their stories. Pending the dragon type this game could go from a deadly game of Trivial Pursuit to a very high stakes game of Jeopardy
• How does a dragon sing? can it play a musical instrument? Might be a literal 'magnum' opus… or this might be akin to howling cats at midnight (but dragon-sized). Results may vary.
• Breeding really weird things as apparently they breed with ANYTHING. Why not breed with local rats and spiders to pass the time? Not just for Donkey anymore. What does a half-dragon / giant alligator turn into? How about a half-dragon basilisk or bullette? Can a demon breed? Note that they breed true with other dragons - even those of dragon-type like wyverns & dragon turtles. Or fae dragons. A fae-dragon mixed with one (or more) colours would have an impressive array of spells…
• Sets up correspondence / sending letters back and forth with another dragon (or any other rival / powerful creature) - using sealed scrolls, proper envelopes or even some mildly enchanted book. Perhaps such as: 'We must fight a duel to the death next year, as agreed - but check out this amazing trifle i found in the back of 'Adventurer Weekly' - the use of cream cheese combined with sour cherries that really makes this dessert POP…')
• Strange architecture can get left behind. Dragons would keep outgrowing where they lived as both their size and the purpose of their lair changes drastically - a bit like hermit crabs that way. Still, they would feel that their last place was so much more like 'home' to them… somehow. Renovation attempts: surreal furniture (what does a dragon-chair look like?), odd wall carvings, exotic wall paints (or bloods?) for murals, weird-exotic creatures destroyed / preserved in different ways (giant jars? stuffed? petrified? glued bone figures? weird furs on floor? skin-bound ornaments?), odd fountains with different liquids and so on. Don't even get me started on mosaics. Greens and even Golds are guilty of this kind of gaudy decoration-obsession.
• Become so good at placing lair-protecting traps that they 'branch out' in to the market / expand / diversify. Dragon ingenious at putting down the most ridiculous things in the wild just to see who falls into them (adventurer group falls into pit-trap that is filled with water and sticky leaves… hears stifled but surprisingly loud giggling from nearby large tree). Possibly selling their trap ideas to local highway men & women.
• Ultimate trap with Mirage Arcane spell: adventurers dungeon-crawl level after level to the very pinnacle of an above-ground labyrinth. At last they make it to the very top room at least a mile off the ground when the entire thing vanishes - allowing them to plummet into some treacherous disaster laid down for them ages ago. Note: dragon must re-cast this spell every ten days or less lest it all go poof.
• Gains new (often harmless) spells and wants to try it on EVERYTHING ('who… just who… taught the dragon Magic Mouth?? EVERYTHING TALKS!' 'Aargh… now the dragon must have learned… Fairy Fire… sprinkles everywhere…')
• Makes variants of a rather-large game of 'chess' (pieces so big it is hard for most humanoids to even move) - flies away for weeks and returns to make one move against mysterious opponent(s) when it is safe &/or reasonable to return. Rules written in / on nearby stones or cliff walls - may also use Magic Mouth on nearby 'audience' statues or even the chess pieces themselves (pawn: 'you can't move me there!!'). Some games may take a decade or two (patience an asset).
• Does sculpture. With mountains. Actually… surprisingly good? This kicks off nervous & hesitant tourism / death-wish / thrill seeker types with travel events too close to draconic lair for anyone's liking.
• Does events that seem whimsical to the dragon (but last for centuries). Sets up schools for bards complete with amazing auditoriums and stages with seating for all races (this would be quite large). Dragon's researching a powerful spell may quasi-accidentally develop an entire wizard's school. If drakes want to see battles they set up huge gladiatorial arenas or even grandiose sporting events for a few dozen decades. Note: dragons could set up 6th level illusion-spells to add to any of these institutions. Spell books that anyone can read, fantastic 'statues' of former heroes, great music or illustrations that add to a bard show, fireworks for a circus or arena event and so forth.
• More on gladiatorial events, but smaller and more grimm. Sets up duels with various undead animations / automatons / abominations against one another. Uses 'Mend' on broken parts and has them fight one another again. Has invented personalities for the skeletons &/or zombies (talks out their voices during 'tea parties'). Has 'dragon-hunters' fight these special undead in various long maze-oriums (watches with 'Clairvoyance'). Places bets with rivals. Makes 'Saw' sequels.
• Discovers 'Dust of Sneezing & Choking'. Due to fascination with death and novelty / allure of this, becomes weirdly addicted to small amounts. Tries it on newly acquired 'friends' / disappointed with results. This is a favourite for teens that are 'Greens'… though they are probably immune anyway.
• Has a recurring (and terrified) slave that goes into town to buy interesting baubles… shops for goods only in towns that are 'small enough' that the dragon could simply wipe out if something went wrong. Well-dressed guy as purchasing agent, claims to be slave: 'i am actually a buyer of exotic and interesting trinkets for a local dragon… you have to help me!!' (nobody believes them).
• Develops odd taste / cuisine for creatures that would kill any creature not immune. Black dragons eating strange slimes. Green might love fresh eye-spores and Purplewormy-poison. Red eating magically 'spicy' things that glow with heat. How do they cook them… and what do they need for added spice &/or flavour?
• Sets up deals with local Medusa for petrified heroes. Amazing sculptures - and so lifelike! Pays too much but has excellent collection. Only visits local gorgon-esque parlours wearing opaque sunglasses / darkness / using blindsight.
• Discovers a local adventuring party group is afraid of legendary local dragon / has been desperately avoiding this creature (PCs: 'The CR on that monster is just too high!!'). Dragon spies on them. Keeps them alive. Does 'Deus Ex Machina' on them a few times just to see how frustrated such entitled characters get for 'not being able to do it themselves' or 'this drake is clearly a DM-NPC now' (or whatever these arrogant low-level humanoid adventurers mutter). As they get more confident that the dragon is their benefactor - start to give them quests ('Geas' / 'Quest') to kill increasingly outrageous things. If boredom sets in drake has them 'quested' to slay each other.
• Twist on above: collects adventurers down through the ages. Many dragons, especially the evil-chromatic ones, may live a lonely (and harrowingly solitary) existence. Finds that solitary existence too arduous / can only relate to murder-hobo 'heroes'. Possibly reincarnates some of them after party-wipe for most humorous results (use 1st edition tables from G. Gygax' Player's Handbook that includes animals).
• Twist on twist above: broken living gifts: dragons keep sending interesting 'pets' (humanoids) off to rival dragon that are 'rigged' with poison / clever explosive runes / cursed magic - these gifts-people will die disastrously within a few weeks or even days after delivery. Two dragons now play a game of save your pet before it dies - investing heavily in various life-saving spells, anti-magics and whatever else.
• Makes all sorts of new variations on 'Continual Light' - in and around special lamps, crystals &/or reflective surfaces. Lights up lair like christmas tree. So pretty. They don't live there of course - can't sleep properly in all that brightness.
• Avid reader. Gets stuck on cheap romance for a couple of centuries. Buys special glasses so as to not strain eyes. Liked 'fantasy' but found dragons were usually the bad guy. Did 'horror' but found they could not sleep properly (for decades at a time - grumpy - sleep-deprived reds are the worst). Like writing complicated mystery stories and seeing if sages can guess the ending.
• Sets up numerous 'false' lairs for self protection. Feels bad that adventurers go so far to get no treasure and only traps. 'Seeds' numerous locations with increasingly odd valuables to creep-out, confuse or baffle would-be hero-explorers. Develops hobby of building dungeons out of abandoned castles, dungeons and cave systems.
• Slays a lich // discovers their phylactery. Gives back spell book with only useless &/or harmless spells (and uses spy-magic to ensure this skeleton-person doesn't regain their deadly magicks). Keeps killing said lich over a series of hundreds of years. Lich appeals to endless sets of adventuring parties trying to gain sympathy for this eternal plight.
• Starts trying out moral-humanoid clothing to 'figure out what all the hubbub is about'. Tries fetish clothing. Invests in getting a suit of armour (with mixed success). Enjoys silks. Cannot figure out how the 'brassier' works. Tries to bring the hat trend back.
• Bad neighbours: drake fakes its own death impressively well (complete with leaving behind real-looking body). Starts developing false rumours that some other horrid & immortal monster has moved in. Possibly fetches and places real vampire counts, werewolf overlords, demon cultists or medusa-queens take over 'former' lair. As rumours grow, heroes rise to challenge and strive to defeat these monsters! In a surprise rush, dragon kills off shocked / unprepared adventurers (would-be heroes die clutching such tools as: garlic, special mirrors, wooden stakes, silvered weapons or whatnot).
• Gets good at spying on own coins with 'Clairvoyance / Scrying' - then allows a specific lair to be raided / pilfered. Carefully tracks down treasure from that lair - but only killing those who spend gold in greedy &/or cruel ways. As money invariably changes hands over the ages it is only a matter of time, possibly centuries, until the dragon gets excellent return on this investment. Bonus challenge: tracking treasures over centuries via rumours, legends and 'the grapevine' through humanoids. Enjoys rediscovery of the same treasure items again and again (especially with magic items that the dragons cannot otherwise use, like tiny swords or those wee, little armour sets).
• Gets impatient with poor 'rushed' mortal workmanship for treasure items. Humanoids waste so much time with eating and sleeping! Dragon sets up shop: has humanoids making vast amounts of the very best jewellery, sculpture, paintings, silkwork, furniture, black-smithery, goldsmithing and so much more. Basically a sweatshop-factory-warehouse on steroids over thousands of years.
• Becomes a dracolich. Doesn't like it. Wants to live again. Needs to appeal to powerful distant cleric (from some humanoid god) to get 'true resurrection'. High priest might agree if dragon agrees to conditions (Priest: 'accept this simple quest' or 'come back to life as metallic dragon' or equally bizarre punishment).
• Becomes shadow dragon - finds the Plane of Shadow a dark & dreary place / not as the brochure suggested. Explores all the border-planes connected to the realms of shadow and finds something Cthulhu-bad // vast abyssal hordes await // freaky chaos event to wipe out world. Needs solid adventurers to save the known realm(s). Time to dig out that rolodex and get powerful adventurers to responsibly save everyone.
• 'Colour' dragon comes down with weird 'metallic' disease. Over time this one 'evil' dragon has done too many good deeds and start seeing their colours taking on a disturbingly metallic hue. Hires therapist. Dragon: 'Should i take on this new role? But what if i just want to… have fun… won't i miss that? I have this new maiden-in-distress and i no longer have a clue what to do with her…' Starts asking player character paladin on 'How To Be Good'. Reads self-help / New Age books. Attends group / gets sponsor / does 12 step.
• Uses Clone spell on self, stuffs a ghost into the mirror-matching form. Now there are two (or more) of the same ancient dragon! Friends? Rivals? Who knows? Makes for horrible neighbours though.
• Related to above: hangs out as a ghost for tax purposes for a few centuries.
• Pick up two levels of 'druid' class so as to hang out as any small, soft, simple unassuming animal(s). Get hunted, preferably by local arrogant & cruel nobles (dragon: 'you should have SEEN the look on his FACE - just after he hit me with that arrow!… can't… stop laughing…')
• Realize locals are giving up all hope because 'fire-dragon raids wipe out their town far too often'. Builds entire new towns, fill them , wait for a century until they REALLY prosper… then… burn them down. Ha! Design them with ancient-packable fireworks / enchants so they blow up Michael-Bay style. Possibly get it a 'copy' of the entire event in a permanent illusion so you are able to watch it over and over. Red dragons would really like this.
• Frame the framers: do any number of horrid things to a populace so that in looks like cruelties done by the local trio of hags. Have these bit-brutal-bitches die by local pitchforks in ironic & fitting ways - for those bitter crimes only ancient dragons could possibly remember.
• Do delightful variants with breath weapon! Blue dragons lay down tracks of water-streams or silver pathways / wires / circuit panels and send their electric shocks down the line to see adventurers dance in exciting and creative ways. White dragons can do 'non lethal' cool-damage to easily defeated adventurers only to thaw and refreeze them over and over (stick their tongues to large metallic objects!). Reds love playing a version of Heat Metal on well-armoured foes. Greens send their love for dinner guests that do not know who their MC is. Black dragons? They get into their acid-addiction entirely too much for too long - even the other colour-dragons feel 'that is a bit much now, don't you think? Know your limits, man….'
• Raise wonderfully beautiful humanoid maidens (elves work well as they live longest) or princesses that are secretly cruel and 'black widows' / wolf-n'-sheep's-clothing. Heroes 'save' these apparently sexy gals (Adventurer: 'I am such a hero… that dragon barely escaped with his/her life!'). Watch (at a safe distance / scrying) as heroes suffer… and suffer… then suffer more (this is a favourite for both green and black dragons). Can be method to take over entire kingdoms given time. Possibly no cruelty could possibly be worse than 'human marriage'. 'Till death do us part!
• Use own blood, leftover scales &/or other regenerating parts to make extremely powerful magic items. Make them sentient? Put curses on them? Allow them to be telepathic so as to keep in touch with new 'owners'? Who knows what kind of 'curses' you can put in! A rogue's bag that makes noise… just at the wrong time. A paladin's sword that makes the wielder look horrid / 'reveal owner as evil' when the hero is making a speech to the whole town. A druid's staff that belches out a hectare of flame whist standing in the centre of that enchanted Great Mystic Weald. Ah… the fun. Any Blue would tell you - best way to keep your warlocks alive and in check is to give them an item… for good times and bad, theirs and yours. Bonus if you use Flowers for Algernon effects from a Headband of Intellect.
• Keep travelling! See the world! These wings are not just decoration after all. If you can shape-change or cover with illusion, pretend to be a helping angel or something harmless. Find out local treasures. Collect. Hire locals if you must to get loot away from those large and annoying 'pesky' armies. You have centuries so take your time, take in the sights and be sure to eat the locals.
• Bird watching. Dragon sight has more uses than just tracking & killing, you know. Ornithology can be a skilled hobby. Why not?
• Cow tipping but for dragons: Be a Real Drake and disturb local wyverns regularly with weird and harmful tactics, tricks and things that they cannot figure out. See how close you can get them to insanity. Remember, they are stupid, stupid, stupid. With a half-wyvern / half-'true' dragon breeding creates something like this race of its own.
• Have / own a functional caravan rumoured to transport very, very valuable treasures - keep eating & looting the highway men that try to sack it. Collect the stashes and exciting treasures owned by the most powerful rogues!
• Take an enchant for a much smaller form. Get swallowed by the local Purple Worm. Break out. Works really well for Black dragons (acid immune) that are entertained with such simple pleasures.
• Go full-trope: Dragon steals and safely captures the family of farmer-lad, leaving convincing evidence his entire family was 'wiped out & eaten by dragons'. Human grows up, becomes a great warrior over the years with complex and brilliant plans to slay this foul-drake-beast and avenge his heritage Bat-man style. When this lad shows up at the gaping mouth of this dread-monster lair all ready and righteous the drake fetches his family and reveals no real harm has been done. Gives them all back, no questions asked. Unharmed. Well fed. Happy. Rich even. The family is a bit confused but glad to see their errant son. Dad: "Jonny? Is that you? I love the new beard!" Mom: "Aren't you lookin' so hot in that armour! Aren't you going to have such a terrible rash though?" Little Sister: "EVERYWHERE you go people talk about you… ugh. Your quests are SO last year. And you are SUCH a goodie two-shoes at that. So. Annoying. (rolls eyes)." Possible 'new' adventures for so-called Hero: has to save human family from contemporary crises: get mother excellent volunteer positions in her community / help younger sister a respectable status amid her teen peers / help chronically unemployed father through mid-life crisis / research what kind of old age home fits these grandparents best. Greatest Evil: discover the worst 'monster' known to our species: typical & mundane life-tasks wear a person down more effectively than any evil dragon could. Oh Hamlet, if you only knew!