Characters are copyrightable, its a similar situation to song compositions vs song masters. There is the copyright of the original picture/song master but separ

Characters are copyrightable, its a similar situation to song compositions vs song masters. There is the copyright of the original picture/song master but separately there is the copyright of the song composition/character. Making your own work derived from the same character or song composition is still a derivative work even if it doesn't directly copy the song master/original picture.