i Agree that vanya is quite extra. But I don’t believe she is at fault for the end of the world. I believe that it is Leonard’s fathers fault. If he hadn’t been abusive to Leonard it never would have drivin Leonard to kill him. Which would have meant that Leonard might not have unlocked vanyas Powers. Just my thought.
I think that number 6 commuted suicide after not being able to deal with the guilt of his powers and what he does. In the first episode he says he didn’t sign up for this after having to violently kill people in th bank robery. As he got older he started to feel more and more depressed after having to do this driving him to kill himself.