So... our mysterious friend now has a name!
Apparently this lovely young lad (?)'s name is Apprentice Vantis.
For those of you who don't know (like me) vanitas in Latin means "emptiness" and loosely translated corresponds to the meaninglessness of earthly life and the transient nature of vanity. Not to mention its an art style typical of the 16th and 17th century.
Hmmm, Ventus (the Blonde who looks like Roxas) and Vantis?
Could it mean something? Knowing Kingdom Hearts, most likely it does.