Honestly I just don't understand this. Of all the qualities that Grifindor house stands PP embodies none of them.

Honestly his is the worst reasoned and fleshed out character in the series.

WHY did he turn his back on his best friends?

WHY did he give up James and Lilly?

If he was so scared of Voldomort then why did he (PP) seek him out and restore him to health?

We never get the answers to these questions. I have read the full series 4 times now and it still seems like the whole stiry turns on his whims yet we never get any exposition.