Let's say that...

[Elijah_Morendale]

...I would like to do a mulligan on Elijah.

Specifically, I would like to make Nadia a full-fledged, flesh and blood character rather than Elijah's split personality.

Would I be able to give Elijah's profile a massive overhaul and include her information and use her as a second player character (obviously for battles I will use one or the other)? Or would I have to sacrifice this account and start fresh with half exp?

[Breaker]

Just do a thread where they reproduce asexually becoming two people.

[Letho]

I don't think there should be a problem with updating your profile in such a manner as long as the new Nadia and Elijah are weaker than the current Elijah. Because if you have two separate characters per account, it would be unfair if both of them were as strong as a single character.

[Tainted Bushido]

The other way to do this, is to simply role play the separate personalities splitting in some way.

I did the same thing with Sarah Dahlios on Lavinian Pride. I'm sure you could come up with an equally unique way of doing so.