I think an interesting thing on all of the characters is that they see no problem working in a place with a killbutton. As simple as saying, "Boom, you're dead," and ... boom, you're dead.
There doesn't seem to be any safety features, if James mixed his drugs badly and went on a shooting spree our PC couldn’t defend herself.
Of Nicholas, if he believes that it really is even than he’s missing part of his brain, I bet Emily could figure it out. If Charlotte can kill nick at any time, and depending on her life might very well do so, but if she does she dies. Nick can kill her just as easily, and thus counts all things even, yet he doesn’t have any problems. That means that where Charlotte has serious reason not to kill nick, nick has no reasons not to kill her.
The obvious way to make this fair would be for every project member to have a “boom you’re dead” thing, or have everyone who works with Charlotte’s, “boom you’re dead,” to have their own that will kill them if they do anything to threaten Charlotte.
Bobby Chaos slightly more than pi believes that Charlotte knew of this before she took the job, and didn’t think it phased her. He felt bad, though not overly much, when he found it had been done without her knowledge. This is an interesting view on human nature, and an odd hope (as in odd belief that there is hope for what he asks) when we see him ask for forgiveness.
Anna, dark and disturbing probably has no problem with the idea of a self-destruct switch for the agent, on the other hand she might. If she had been given one than she wouldn’t be able to shoot the people she’s going to if Cassandy goes bust. Also she seems to support the pacifistic views Charlotte can have, this is a stark contrast to what little else we know of her, it makes her about as interesting as Emily. It also makes it hard to judge her stance on the “boom you’re dead” function.