Either one of two people:

Exdeath: not so much to meet with him, as more as to set him loose upon the world. he has superior magic in the begining which gives him a leg up from just kefka. and i guess i would meet with him and be his magical apprentice, and tell him about how you take out the nuclear powers first then you can take over the world.

Vivi: he has a talent for black magic, i would definately like to learn from him. either that or the original black mage from final fantasy 1.