I got all excited about this thinking you were asking about ally spirits. Then I re-read your post...Mentor spirit.
From an absolute rules perspective it isn't addressed.
Start with the player and the GM talking about it. Consider the story. It could be cool either way.
Also, consider the mentor spirit. Chaos would be fine. Fire-bringer less so.
Kinda like the movie "The Prestige" the mentor spirit griefs the personality who venerates it. "Oh, you like me today".
The mentor spirit could be trying to bring the rogue personality back. So if the player were ever considering getting rid the the quality the mentor spirit's help/intervention could be 'how'. Even if the player isn't getting rid of the quality, you cold have fun RP as the spirit tries to exert influence over a personality who won't/can't change.
Good luck. Sounds like fun.
