4. Did Klaus Hate Elena?
When Klaus came to Mystic Falls, he was determined to use Elena for his ritual which meant Elena's death. Elena accepted her fate, as long as those she loved wouldn't be harmed. But Klaus still did his best to torture her mind when he decided to use her aunt Jenna in the ritual as well and killed her.
Maybe Klaus hated Elena because she looked the same as Katherine, the girl who made a fool of him five centuries ago. As it's been established in the show, Klaus isn't the forgiving type.