Snape : Karkaroff’s Mark’s becoming darker too. He is panicking, he fears retribution; you know how much he helped the Ministry after the Dark Lord fell. Karkaroff intends to flee if the Mark burns.
Dumbledore : Does he? And are you tempted to join him?
Snape : No, I am no such coward
Dumbledore : No. You are a braver man by far that Igor Karkaroff. You know… I sometimes think we Sort too soon
[Harry Potter and Deathly Hallows, The Prince’s Tale]