GP is not the parent (P) reply, but the grandparent reply, i.e. the one written by "omgtehlion". When you write a reply, P would be the one you're replying to.

GP is not the parent (P) reply, but the grandparent reply, i.e. the one written by "omgtehlion". When you write a reply, P would be the one you're replying to. GP is the reply the person you reply to was replying to