Zexion is Number 6 in Organization 13. He is the Nobody of Ienzo, who is one of the 6 apprentances of ansem the wise. Vexen, Number 4, also Even, was his mentor when they were still human. Ienzo's parents died when ienzo was at a very young age, so Even looked after him. But now, it seems vexen dispises zexion, and is forced to work with him in KH re:chain of memories.
Zexion prefers to mind his own bussiness, unlike xigbar who seems to enjoy eveas dropping on people. zexion dislikes being interupted, but is not short tempered. Zexion is very pacient and smart, like his mentor, Even, unlike his partner in castle oblivion, vexen, whom is very impacient, especially to zexion. vexen is seen pacing around after zexion is trying hard to identify a character among the basements floors. Zexion prefers to have others get their hands dirty, rather than his own. He does not like getting his own hands dirty.