Celadon is an anomaly among dragons. No one is sure if they are an extraordinarily old copper dragon whose scales have turned to verdigris, or an evil green dragon.
What is known is that Celadon is old. Older than the The Elven Kingdom where their forest lair is. Older than the oldest trees, possibly older than the gods. They have seen kingdoms rise and fall, mighty heroes, arrogant villains, brazen thieves, in a way you could say that they have seen everything. Since they have come to have a been there, done that attitude, Celadon no longer has the avarice that defines the rest of the dragons.
Not to say that Celadon is without riches beyond imagination, but the material is not what they have been looking for. The dragon has been hoarding not gold and riches, but secrets and magic. The Great Dragon sleeps on their hoard, and sends its mind out into the dream realms collecting these things. Celadon shares knowledge via their The Castellan. The Castellan is a Warforged, who was created by Celadon to act as their caretaker and mouthpiece.
Celadon rarely wakes, but it is said that they will wake for the promise of trading arcane secrets or gossip of the rich and powerful. While the dragon is more interested in knowledge, stealing from the dragon will enrage it. The last time Celadon's ire was raised, the Destruction of Nickel Depths was the result. Celadon dug through the side of the mountain to destroy the Enclave and all of it's Mountaineers.