5. Why Didn't Klaus' Siblings Leave Him?
When he was still a human, Klaus and his siblings got along well enough. Especially Elijah and Rebekah had the tendency to protect him from their father Mikael who hated Klaus.
The three young people even swore that they'd be together always and forever. But Klaus had betrayed and daggered his siblings multiple times so it's surprising that they never left him for once and for all. If Katherine could run from Klaus for five centuries, his siblings would be able to dodge him as well if they wanted to.