Dragons in DF are so utterly... boring.
Yes, they're powerful, they are dangerous to deal with, but they're utterly boring.
So, as a part of myth and magic update I propose to add the following changes to the dergs:
1. Randomized breath weapons. Not every dragon should breathe fire. Some should breathe ice, acid, poison, electricity or even other stuff.
2. Dragon personalities. I think dragons shouldn't be just dumb beasts to be disposed of. I think they should be intelligent and have varying personalities, just like the other races. Yes, some would want to burn and destroy everything in sight, but some should be neutral or even friendly/helpful, so the player, both in fort and adventure mode would have to think if he/she really wants to kill that dragon and risk angering neutral or even friendly dragon.*
3. Dragons should know advanced magic and be able to teach them to dwarfs and other civs if they're friendly. They have lived for centuries, if not millennia so it makes sense they'd pick up some tricks.
*Dragon personalities explanation:
Decided to put it after the asterisk, because otherwise the second point would be too long.
Bad/angry/evil/whatever you want to call it: These dergs just want to burn everything in sight, either because they were wronged in the past (looking at you, Alan!) or because they were just born that way (being raised by "evil" dragons increases likelihood that the child will also be evil). They can be turned neutral, but it would take a lot of time and appeasement, they also would mellow over the time (centuries) given they aren't disturbed and angered further.
Neutral: Neither good, or bad. Be careful, if attacked they would turn into bad/evil dergs, though unlike the pregenerated evil dergs, they'd not be fully gone, allowing players to right the wrong (though if too much time passes before the player makes things right, they'd be evil for good). If the player decide to be nice to them, they'd slowly become friendly/helpful dergs.
Friendly/helpful: Nice dergs. These will help players in various ways, from making nice ash piles where the enemies once stood, to helping in forges and kitchens (and anywhere the fire would be useful). They also make sure to control the range and the temperature of their flames, although accidents do happen. They would also teach and learn from the local wizards that are either a part of or friends with the civ these nice dergs are part of.
While I've described it as 3 states, I would actually like this to be a spectrum from fully bad to really friendly. Some "evil" dergs would still help out if it aligns with their interests, while some good dergs are good to the point of refusing to hurt a living thing, even if they're the enemy. Or on the flipside, would help dispose of enemies or making weapons, but refuse to teach any magic either because the dragon in question thinks the mortals aren't yet ready, or wouldn't be able to safely use it.