Vincent Von Drathen dancing with "his" symbiont / pet monster

It usually follows the young mutant's orders -- but it has freewill. Oh, there are advantages and disadvantages to being never alone. Fortunately (??), it resides in an extra-dimensional hidey-hole.

However, the 2 share a common center of mass. This affects how it can manifest its tentacles in "real space." Somehow, the number 17 comes up a lot when trying to quantify their individual and combined powers. Vincent neither knows nor cares why this is so.

He has not assigned a separate name for it any more than he'd give his left big toe a separate name. Others, however, have given it multiple nicknames.

Vincent is technically intersex, and not everyone is convinced that he's actually a boy. Vesperia in particular considers him to be a tomboy. His incredibly loyal girlfriend, Kali Neelam, thinks that he's a boy. And that Vesperia is insane.