We're going to brook a deal with a vampire? He's already told us what he has to offer: "wealth, power, immortality." Since when do the GOOD heroes start making shady deals with EVIL vampires? Why is this even a discussion? His existence is an anathema to everything I fight for.
I'm all for drawing information from him, which is exactly what I did. However, he told me point-blank that he knew nothing further, and I believed him. So, with that avenue exhausted....
Wait a minute, we're not seriously thinking of saying, "Well then, sorry to barge in unexpected. We know you'd prefer not to fight so we'll respect your wishes. Cheerio!" And then walk out of there, all apologetically? Cripes, what a wussy bunch of adventurers we'd turn out to be!