It’s an undead baby dragon, produced by a failed magical spell. It probably would be cute if it weren’t partially decayed.

Young drakes are relatively defenseless. They are born with relatively soft scales, which are shed and replaced with harder ones as the hatchling matures. Once a hatchling’s wings grow in, it marks the beginning of maturation. At this point they are often capable of hunting on their own.

Franciszek was adopted as the Kaminsky family's darling baby drake. He was walloped by a cart, then partly eaten, then brought back to life (in a way) by a witch's trainee. His owners recognized the "playful and ebullient" hatchling as theirs and took him back home where he belongs. He has changed a lot since his humans last saw him, not least his appearance, but they still see him as their darling baby. The only changes in the daily routine are that he's in a muzzle nearly all the time and gets bathed more often.