Buffy/HP Xander, Harry, Magical

In the last seconds of her life, Lily Potter knew the bitter and heart-breaking taste of betrayal. They had done everything they could to keep their son safe. As the Dark Lord Voldemort uttered the words “Avada Kedavra” She cursed Albus Dumbledore and the order of the Phoenix and made a final wish to protect her son and stop the plans of the manipulative old goat.

The wish is heard by D’Hoffryn changing Xander’s life forever.

Cursed into the form of a Cat Sith (Large black cat (as large as a dog) with a white spot on its chest), Xander is tasked with care and protection of the wizarding world’s boy who lives until Harry is finally safe not only from Voldemort but the manipulations of Albus Dumbledore and the Dursleys also.

From Wikipedia

Cat Sith – Thought to be a Fairy or witch (or in this case wizard) that can transform into a cat 8 times should they transform a 9th they are stuck as a cat. (In this situation Xander is a cat that can transform into a human 8 times ((for a short time perhaps a day or three)) before being stuck as a cat forever.) They are thought to be soul stealers of the recently dead. They are also thought to bless or curse a household (cough- cough Dursleys) if a saucer of milk was or was not left out for them.

When Harry was left on his aunt’s porch that cold October night, he wasn’t alone but had a furry guardian watching over him.

Imagine the havoc and vengeance a Xander err Xan-Cat could wreck (cackles).

Prophecy? Ha!

Possession!? Been there done that.

Vengeance? Duh! My Ex was a thousand-year-old vengeance demon who liked to boast.

Bonus points if you can work in that the Goblins and House Elves recognize what if not who Xander is and fall over backwards to ensure they do not infer the wrath of the mythical entity.