"Time really does change your perspective, huh?"

While fighting a malnormal who could manipulate time lines, Vanitas ended up in the past. Except that it wasn't his past, but his partner's.

He get's to meet the little version of Noe, get's to see what lead up to the way Noe is in the present, meets the infamous shapeless one.

But most importantly, he cures Louis De Sade. He ends up changing the course of Noe's life, his purpose for being with Vanitas and most of all, the vampire's feelings for him.