Two Potions of Blackness

Lord Voldemort and Severus Snape had a few commonalities . . . they brewed the same potion, but each for different causes- which was the one with the saving cure? Each were very skilled, fought for what they wanted, what they loved, with zeal, save for the one did not understand love's meaning. One did, yet, no one knew of it. Comments are always welcome. {Not for faint hearts}