I understand the amount of work that may be involved in this endeavor, but it would be nice to have. While playing the DB I enjoyed being the creepy menace that could choose to remain silent, and the reactions that followed, were a nice touch. Afterwards, however, I go out in to the rest of Tamriel, and all of a sudden I'm this very talkative, super-helpful character that I really don't want to be. So I end up rushing through the text like I don't give a damn, so that I can play like a character that doesn't give a damn, unless there's money involved.

The overall problem, I think, is that DLCs like the Thieve's Guild and the DB are too isolated, and don't really mesh in well to the already established world. They feel tacked on instead of feeling like they're part of the foundation of the game.

This leads me in to speaking about missed opportunities. IMO, allowing players (as a member of the DB) to target certain npc officials in Cyrodiil, would be taking a covert approach to changing the tide of battle, when the odds are stacked against one side.

Or the Thieves guild player, could have been useful in stealing a document from an opposing side that's suppose to receive a report that a resource or castle is being attacked by their team. There would be a timer set for the players to intercept the npc messenger before they make it to camp. This swift messenger would be very fast, making it a necessity to either have a fast mount or PC. This makes taking over land a more complex task than simply attacking everything that isn't your faction color. This would also give the benefit of being fast a more significant purpose. Some players would have to be assigned the task of chasing down this celerity character, before their plan gets shot to Oblivion.

Summary: I want my character to continue being creepy throughout all (before and after) missions, with dialogue to match. There should be DB dialogue, Thieves guild dialogue, werewolf dialogue, and vampire dialogue, to name a few.

Examples:
Thieves Guild Dialogue - Can you get that for me? PC reply: Yeah, I've been known to lift people of their burdens; but it'll cost you.

Dark Brotherhood Dialogue - I won't tell you anything. PC reply: You know, I usually function on contract, but I will happily kill you for free.

Werewolf Dialogue - You don't scare me! PC reply: Look at me. [Eyes glow] Am I scary now? Y-Y-Yes ... yes you are.

Vampire Dialogue - Damn Bloodfiends make me sick. PC reply: Speak badly of my fallen brothers and sisters again, and you won't even be able to bleed to death, when I kill you.

Also, why can't being proficient at stealing be an asset to the war? Or assassinations of an official target cause npc's to cause less damage because their morale is low, and they're scattered without a leader?

What about having the option to release a stampede of horses over a camp, creating a distraction, that allows other team members to gain an advantage.