I love the bit about the body temps/conscious control. Hope it's okay if I geek out a little about my own setting/character. ^_^;;

My dragon Princess works the same way on the "internal furnace" stuff. Her internal dragonfire lets her raise/lower her body temperature, and while she's protected from cold because of it, she's only protected as long as she can spend that extra effort. Meaning more food is needed. She generally keeps her body temp at around the "usual mammal level" both out of habit (being a former human) and because it's a good compromise between feeling energetic and expending effort.

She's also immune to heat, and has been tempted to test it by standing in fire. She hasn't had the opportunity to try a volcano, but she'd likely find a similar experience, the gasses making it hard to breathe. ^_^ If she wasn't immune to heat/fire, breathing fire would be horribly dangerous...

She hasn't requested the temperature be above "normal room temperature", because she hasn't really thought about it. And living on Terra, there's no real HVAC system to mess with. She has gone into what she calls "Space Heater Mode", warming a room during the winter months. She can get her body temp to close to the boiling point of water, but higher temperatures take higher amounts of effort, kind of like lifting weights. I figure since her "no effort" body temperature would be closer to a sluggish lizard, she doesn't feel the same "this is too cold for me" sense that the Fire Type pokemon seem to feel here (though I could be reading wrong into the cause of their feelings).

I figure dragons on Terra have evolved more feline traits, because the body temp thing lets them be more active than most reptiles, and so they're more active hunters than passive. So she has a body style that more resembles a cougar or tiger mixed with a crocodile, and moves with a feline grace and style. (Even if she has some "dog" body language, with her tail wagging when happy. It swings down to thump against the floor when she's annoyed, likely evolved as a "startle target/display power" type of response. Maybe "alert other dragons" but they're usually solitary, so maybe not.)

I suppose that would be an interesting way to go about things, that for them the colder things are the more alert and predatory they'd become since they'd need more food to compensate. And in contrast when things are warmer they'd seem to be much more chilled out since the need to eat isn't as severe.

As for the pokemon thing it isn't too much a "too cold/hot" as it is how energetic they are. Granted they'd complain about things but they can control their own body temperature to a degree. But for them at the extremes it's more like the difference between someone who just woke up and hasn't had a cup of coffee yet vs someone on their third cup

I think it's less "Colder temperature = more alert", I was thinking "Colder temperature = get hungry again faster". Which, if a dragon were to try to settle in a colder region, would lead to them needing to hunt more often. Potentially getting more cruel and brutal in their hunger. With the deck stacked against them, though, I think most prefer to avoid it if they can. Or curl up somewhere sheltered and hibernate when their body temperature drops from not being sustained.

It's possible they might spend most of their time sluggish and near torpor, and then when they realize something's there, expend the effort to warm themselves up and get ready to move. It'd be a frightening sight for a mound of snow to stand up as a dragon shakes most of it off, and the rest melts and evaporates into steam.

(Most dragons on Terra aren't much smarter than a dog or wolf or something, though. Princess is an exception because former human. They're also only the size of a large dog/wolf, no worries of mountain-sized dragons destroying cities. ...but villages made of wood and straw are pretty flammable, so one dragon is still a pretty major threat if not dealt with. ^_^;; )

I haven't really gone into a lot of work establishing exactly how the body temperature thing works, most of it is just "A consequence of being able to breathe fire and also being immune to it". One chapter mentions them trying to boil a kettle of water by putting it on Princess's side, but I didn't actually state whether it was successful. >.> Mostly people are just surprised that she's warm, when she lets them pet her.