What does a dragon dislike?

Most dragons aren't scared of anything but if they find a beast way larger than themselves, they certainly won't try to eliminate it. Also most dragon hatchlings or "chicks" are afraid of the hydra for its preferred food as other dragons' children. If a hydra is VERY hungry, it will detach one of its many heads, which will turn into a chick for the hydra to eat.

I don't know who made that up, but it's not true. What a dragon is afraid of depends entirely on the dragon. All dragons are different, just like all of you humans are different.