Well that brings us back to the use of italics then, the standard use of which has been to emphasize or convey emotion/thoughts from what I've seen. I know they've been used for a different purpose, though I don't know why, but using them to show a thought or such can still work even in a first person format. It just depends on where and how it's used in a post, in which case I generally italicize a full sentence for a thought, and a portion or word for emphasis.