I've decided to overanalyse them again and put them in a different fandom situation.
IF HMS WOULD GET GET MANIPULATED BY A FOUR-DIMENSIONAL, BIRTH-DEFECTED TRIANGLE!
Mind is most likely to. It would take him a while, but he would cave, if Bill had the patience to work with him. He would cave because Bill promised him the thing he wants most: power and recognition from the other two. Being promised that he'd finally be recognised as important to Soul and not as an annoyance to Heart, made him accept the deal.
Heart would, but Bill would have to do it based on his insecurities. Heart is more mentally guarded and would probably deny any promises that Bill would give him. Until Bill would use his emotional instability against him, making Heart deal with him in an attempt to prove him wrong.
Bill would try to team up with Soul, since they both have the ability to see through different timelines. Soul would rather die than accept this, though he knows the offer is tempting. Bill's numerous attempts to get the (arguably) strongest side as an ally would all go to nothing, as Soul would usually yell or threaten death.