Rodolphus could still feel the stinging pain in his arm, his anger at that fuelling the Cruciatus he held Vaisey under.
He would see him dead for his own foolishness, his usefulness only half as much as it was when he was with the head of the aurors. The screams and cries were music to his ears, and he looked up to see if Bellatrix was watching.
That's when he saw her duelling. Not playing with Muggles, but duelling. Either she had forgotten her own condition, or she was unaware of the fact her own magic could go so wonky at the present time? Looking down at Vaisey, he stopped the curse.
Vaisey seemed to be suffering greatly from the Cruciatus. Rodolphus needed to get to Bellatrix - protecting her and their heirs was paramount. As he turned to leave, he cast one final blasting curse at the wizard lying there for dead.
As he turned to his wife, he made a mental note to rid himself of the mother later - she would be of no further use to him.