I usually have a really strong squick around non-con, but in the case of Death Knights, part of the thing I LOVE about them is that they're always subject to the whispers of the Lich King (Arthas or Bolvar, doesn't matter. A benevolent mind-controller is still a mind-controller!) If you have any interest in exploring the tension between what Koltira and Thassarian feel for each other, and the demands/expectations of their Master, that would be lovely. Especially something where the boys might want to be kind/loving/romantic/consensual with each other, but the mind-control injunction to cause pain/harm/trauma/heartbreak is something that is constantly causing tension and making them act other than they would (or having to fight against it/understand).
I don't know if I articulated that very well, but those are my fuzzy thoughts.
In this case, the whole violence/non-con thing would really not work for me, and non-con in particular would fell squicky and totally out-of-character.
Mostly, I want more banter and adventure-avoidance. However, if you want to give me backstory, or have them get dragged unwilling into an adventure, that could be a lot of fun. Basically, I see them as similar to Vladimir and Estragon from Waiting for Godot, or Rosenkrantz and Guildenstern from R&G are Dead - that is... more commenting on the world around them and only participating unwillingly. So yeah, they might be a good pairing for snapshot interactions, rather than a fully-developed story.
Go to town. Give me the crackiest crackfic ever to crack the world. Give me fourth-wall breaking crack. Give me crossover crack. Give me sexy, well-written crack.
My only squicks are non-con. I'm not usually fond of M-Preg, but I don't think I can make any such restriction when I've just asked for crack :)
I love VanCleef, and I think he has a totally legitimate beef against Varian Wrynn and the nobles of Stormwind. He rebuilt their fricken city, and they didn't pay him or his workers because they're cheap assholes. Man, I want the Defias to tear that shit _DOWN._
But of course, Matthias Shaw can't let that happen. That is a recipe for epic, tragic conflict.
Bonus points for VanCleef kicking Wrynn in the junk, whether actually or symbolically.