You, Lori's first child, aka Carl's older sibling, had known about Shane and Lori when they thought Rick was dead. You hated Shane from the beginning, you were always close with Rick and this temporary "replacement" irritated you. But when you figured out he lied, and Rick was alive, you just hated him even more.

Shane was close with Carl, and you hated it. You tried to tell Carl he was bad news, but in his eyes Shane was some sort of hero..so you tried to talk to Shane.