I was battling writing in third person with Kri way back on Isilme. Kri is just -not- a character that is best played in third person. She has too much to say to be held back by the constraints of some other narrator, and after switching over to first person, I realized how much easier she comes across.
So if your character wants you to write a certain way one post, do it. Don't be ashamed if you want to skip around styles either, but as long as you can find a way that YOU want to write, that is all that matters, in my humble opinion.
This is the last place that you should feel restricted by writing style. So, just do what I do, and have some fun with it. c: