I think I might prefer if Bela offers up a solution as a way to keep Dean from killing her, especially rather than out of a romantic or even purely sexual relationship. Despite similarities, I can't really see them as friends either. And I suspect that Bela is either going to screw up again and piss the boys off, or her lifestyle is going to land her in serious trouble with something else again - maybe something that could give Sam and Dean inspiration on getting Dean out of his bargain.

I think Ruby's going to dangle the bait just long enough to push Sam significantly into the dark side (or appear to perhaps), and may eventually even only hand over her solution only if Sam has to make a serious deal with her. In fact, I wonder if her solution may not directly tie into Sam becoming this evil leader. After all, I would think that no matter who holds Dean's contract - if Sam can become someone higher up than that demon in Hell, he should be able to call it off.