Vaarsuvius wouldn't go to the same afterlife; they seem to be segregated along alignment lines (as per the Great Wheel cosmology), and as everyone keeps forgetting, V is not good-aligned. I have him pretty much pegged as TN. Even if V was good way back in the Unholy Blight strip (s/he wasn't, Rich admitted having him/her sickened there was a mistake) he certainly isn't now.
Oh, and what's with all the spoilering of anything remotely speculative? Since it's all speculation, it's not like you'd be giving anything away, people. All it does is make the thread annoying to read.
I don't know that "I accept your offer" to the imp would work - remember, it has to be the right 4 words to the right being at the right time for the wrong reasons. To me that seems to imply that there would be a right reason to say those words to an imp, which I find hard to believe (for a non-evil character).