Saving Ravenclaw (Severus x Rowena)

"Severus, what I want to tell you is that you must travel to the past so that Rowena Ravenclaw arrives safely at her destination," Dumbledore explained, with infinite calm, but without stopping drilling him with his blue eyes. "It is the only way to ensure the survival of Hogwarts."

"I'm afraid, Severus, that you are the only one with the necessary skills for this mission," Dumbledore explained. "From what I imagine, Voldemort has sent death eaters back in time. And who better to take on a death eater than another death eater?"

...

Will the potions professor manage to save the course of history?