He is not real ''deerchild'' xD It was Leartes in his sillyness just mistaking him for one...that's it until he realized that the boy is not deer but a devil xD Real deer-children are children living in the deer tribe in the forest. They are peaceful and have deer-like-horns [link] , not goat-like ones-which you can see on the that boy.
No, he just transformed so did his whole body, the stripes just moved randomly onto other part of his body this time at tusks but they can move into anything-claws, spikes etc xD
No no no! The draw is awesome, it just was a suddenly transformation, so I got confused And I was just kidding I just think is cool to call him deerchild, because "devil" sounds too evil for me, so I use deerchild to let him cute :3