I want to talk about Dragons, as they are in Dwarf Fortress right now, and what they possibly could in the future. Right now, these beasts are not valuable in terms of killing them, nor are they as threatening as they could be. While they will definitely achieve flight, I think there are other things to consider about dragons: Lifecycles, and the impact that would have on their abilities. I was considering Dragons in this game, comparing them to the ones in Castle of the Winds II. In that game, dragon's can't fly. But they didn't need to, since their breath weapons cover several squares, and their age determined the amount of coins they dropped, along with their overall power.
Something similar in Dwarf Fortress wouldn't be a bad idea, especially considering that world generation takes time into account, along with the wide variety of possible items in the game. So here is a basic rundown:
Dragons should be given life cycles, and power accordingly. Basically, the world spawns many weak hatchlings, which will be replaced by the appropriate lizard as historical figures are culled. Furthermore, dragons are attracted to wealth that is based on jewelry, metals, and fine crafts. Likes bedding on coins and such. As time goes by, matured dragons will create hatchlings of their own, some of which will bother the player and other civilizations. Below is each stage in the life cycle, in terms of abilities and tendencies for a dragon.
Hatchling
-No breath
-Slow
-Preys on anything (inexperienced)
-Weak hide, no scales. Just like leather.
-Grounded
-One square in size.
Young
-Single tile breath
-Slow
-Preys on wildlife, but avoids sentients and megabeasts since it is smarter now.
-Thick but scaly hide.
-Grounded
-Two squares in size.
Mature
-Three tile breath in a line.
-Medium speed
-Preys on both wildlife and sentients, but avoids rival megabeasts.
-Scaly yet metal hide.
-Flight
-6 squares in size, two lines in a...line.
Old
-Nine tile breath, in a square.
-Medium Speed
-Preys on anything.
-Armored hide - metal, diamond, scales
-Flight
-Nine squares in size.
-Colossal headbutt (from the ground, to cause internal damage to fortress.)
Ancient
-Huge breath, 25 squares.
-Fast
-Preys on anything.
-Diamond, Metal, Adamantite, Scale hide of protection.
-Flight
-25 tiles in size.
-Colossal headbutt (from the ground, to cause internal damage to fortress.)
The hide of a dragon becomes increasingly tough with age, because the materials a dragon has bedded on would become part of it's hide. Just like with Smog in the Hobbit. Accordingly, the hide yields the appropriate base materials, and a number of dragon scales. Hopefully, dragons in the style I have suggested would be suitably epic and rewarding foes in Dwarf Fortress, if accepted.