Re: Second pair no kicker/tons of backdoors/passive stealer; line?
 

c/r b/f b/f depending on his aggression.

I also like c/c c/c b/f or c/c b/f b/f better than your lines but I think c/r bet bet is best.

btw 8% pfr is usually one of those guys that is randomly raising any two cards 8% of the time instead of top 8% in my experience.

Re: Second pair no kicker/tons of backdoors/passive stealer; line?
 

I don't know why people seem eager to put an opponent in the "doesn't raise his top x%" of hands catagory due to a strange vpip/pfr combo. Sure these players exist, but my experience is that its the exception by a long shot. Therefore, I'd need a read before giving this guy a range other than "somewhat stronger than a typical button steal."

Re: Second pair no kicker/tons of backdoors/passive stealer; line?
 

check riase call down if threebet assuming no A on turn or river.