It's not uncommon to be thousands of years old in my universe. Some are even as ancient as many millions of years old. There exists dragons in my story, and their silver coloured blood can be used to prolong lifespans. The blood of most dragons are harvested in large facilities, sort of similar to today's pig farms and such. But then there are free dragons that are hunted down and tapped for blood. Dragons are born wild, but become sapient and able to speak as they age.
Hmm. Can they cast spells or change their form? Some dragons (e.g. D&D ones) can, especially when they stop being dragonlings.
