After finally finishing the main quest line for The Dark Brotherhood, the Night Mother asks me to go see a new contact.

The contact is a Corrupt Agent at the Penitus Oculatus Outpost in Dragonbridge.
When I enter the Outpost the agent sits at a table, drinking and I can't speak with him!

I've tried stealing but he just says: "Oh, I guess you really need that." And when I kill his buddy he's like: "Hmm, guess he deserved it."
I've heard that this quest isn't the same for everyone but if you have had/are having the same problem and have a solution, please tell me...

If you have the console you can use complete quest commands... If not, then reload an earlier save. Nothing you can do to fix it now.