The Vampire Diaries - Season 2 Episode 7 -

Katherine becomes a threat to Mystic Falls and Stefan and Damon decide to stop her at the Lockwood's masquerade ball. Bonnie, Jeremy, Alaric and Caroline help the Salvatore brothers, but Katherine brings the witch Lucy to protect herself. Meanwhile, Matt picks a fight with Tyler, but Caroline hits Matt avoiding the fight. Sarah is also compelled by Katherine to pick a fight with Tyler if Matt fails.