He became a werewolf, she became a witch and a lesbian. One of Buffy The Vampire Slayer's cutest couples has some serious odds stacked against them, but finally Oz and Willow are back together!

Or at least the stars who played them are, since Seth Green is guest starring on Alyson Hannigan's CBS sitcom How I Met Your Mother.

Find out more (and see another pic of the awesome twosome) after the jump!

"I’m in the makeup chair again and next to me is !!!!!!!!!! YAY!!!! Reunited and it feels so good!!!!" Alyson tweeted from the set of the show, along with a pic of herself in a black wig (presumably, for a flashback in the series) next to her former TV paramour.

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Then, like a stake to the heart (in a good way), we get a picture of Seth, Alyson, and Alyson's daughter, giving us a glimpse of the happy TV family that never was. Now Oz and Willow fans can finally rest, having seen what it would have looked like if the two had worked it out and had a baby together.

Of course, if Seth is looking to rekindle the romance for real, he has some competition ― Alyson is married to another Buffy star, Alexis Denisof.

Will you check out Oz and Willow's reunion on How I Met Your Mother? Tell us below!

(Photos via Twitter.)