Black Family Line

Ursa Walburga Black, Regulus and Sirius' little sister, has never considered herself a good person, but when almost a year after her older brother ran away from Grimmauld Place she finds her twin brother tangled up in the arms of none other than James Potter, she manipulates none other than Voldemor so her brother can be free, maybe even happy. She convinces him Regulus will be of better use as a spy and there's only one way anyone will believe he's switched sides is if he does the same thing his brother did, run away and the Potters have already taken in one stray Black... but that wouldn't be enough to convince Dumbledore, of course it wouldn't, but they've all heard rumors about the nature of his relationship to Grindelwald, if Regulus appeared to be in love with Griffindor's golden child...That's when Bellatrix reminds them he's not the only Gryffindor the old man notices, and they all know the black's motto: heir and one to spare. That's how she ends up living with the Potters and in a fake relationship with Peter PettigrewIt's a SLOW slow burn and fake dating with good Peter Pettigrew