Don't smother your Troll Dragon too much. They're a bit - well, let's call them shy. When they're not brooding in their habitats, they like to lie in wait under bridges, occasionally popping out to nick fruit from the carts of farmers passing by.
More than anything else, Troll Dragons like to tease the other dragons in their habitat. Troll Dragons drive their neighbors to the brink of frustration by poking them from behind, then flying off, leaving them wondering what happened. This will repeat until the dragons become irate.
Sure, Troll Dragons have their quirks, but they'll warm up to you after a time. You just need to be firm with your dragon - be sure to teach it right from wrong, and teach it to not be a pest to dragons who anger easily. After a while, it will become loyal.
Epic Troll Dragons are clever. TOO clever. They can pull pranks on the best of caretakers. You don't want to be around when an Epic Troll Dragon decides to play a prank on you. Keep your Epic Troll Dragon as happy as possible, and maybe recommend other targets for its mischief. Like Rex. He deserves it.