I'm a new dm and i'm studying CoS so i can run my 2º campaign, i'm reading Strahd goals and notice that turn Ireena and find Rudolph can sustain itself even after Strahd and the party become enemies.

But i can't understand how Strahd tests a cadidate, he will just come to someone and say "I challenge you to defeat my vampire spawn 1v1", "I challenge you to a chess match against me", and how he test then after they become enemies? Strahd jumpscare the party in some random moment, down a PC that "maybe"(his ego is so inflated to accept anyone that isn't from his bloodline so he will never accept) is worthy to succeed him, places a reverse bear trap(from saw) on him and hide the key in somewhere dangerous in barovia?.

Why does he even wan't a successor? he is fucking immortal, the successor will wait a eternity so he can start to rule