Previous question answered while I was posting.
....Who is your second in command after becoming Listener?
Arquen.
But I have to leave. Pending confirmation here is my question:
What how does Gogron gro-Bolmog of the Dark Brotherhood claim he can prove he has a "relationship with with Telaendril?
Since I have to leave, here is the answer. You are on your honor not to peek:
Spoiler He says he has her undergarments.