He can be very dangerous and has killed multiple. His is an Original Hybrid. He has a brother named kol and Elijah Mikaleson. He also has a sister named Rebekah Mikealson. Klaus also knows Elena gilbert who he killed but is still alive because she is a vampire and doppleganger. he knows Damon Salvatore who is a vampire and has brother named stefan that is very loyal and protective. Damon is more of the bad brother and stefan tries to do right. Damon and elena are together. Stefan is elena's ex boyfriend but stefan married elena's best friend who is caroline. Caroline and stefan are both vampire and both were tuened by elena's evil doppleganger who is Katherine. Rebekah did kill elena and caused her to turn into a vampire. Bonnie is also Caroline and Elena's best friend. Bonnie is a witch but was the anchor to the other side. Klaus also had a love intrest with caroline but its over now. Mlaus remembers everything and is tryin to help elena and damon find their daughter.