Lol. I'm doing the main storyline now because I have to get the other elder scroll before I can go stop the vampires some more.
So in the main storyline I stopped by at Elenwen's place (Thalmor Embassy) with a fake invitation. She knew my name in that note so when she asked my name in person I basically pretended to be a kiss ass and was like "OMG You're Elenwen? So Much Elenwen. So amaze. Wow" and she was flattered and everything and later left forgetting that she asked my name.
I got someone to cause a distraction, snuck into the kitchen and beyond, put on all my armour and weapons and stuff I had smuggled in.
And I started shit.I was killing any Thalmor guards that stood in my way, I robbed gold and other valuables every inch of the whole place (I even found a damn safe!)
I found out my Dawnguard Rune War Axe can shatter wards with even a light hit which results in the ward user staggering,
so much awesome (normal weapons, even with normal enchantments, don't do anything to wards).
I then stole all of their intelligence including Dragon related stuff, killed the interrogator, saved my inside man (or elf I should say) and freed the sole prisoner. Then escaped.
I gave the Thalmor a black eye. Elenwen,
now you can call me a threat.
Bitch.