Harry x Hermione

Despite looking to be cured of her cat girl transformation, Hermione went on the next two years blissfully unaware that it was dormant and mutating.

Come 4th year, after a few days of stuffing herself at every meal and a unbearable pleasure in her nether regions, Hermione is stunned when one weekend she wakes up as a cat girl again, only this time she's many times fatter and extremely bottom heavy.

In heat, she turns to the one boy she can trust AKA Harry, which leads the duo down a path of happiness for them, a few others, and a terrible one for many others. (Dumbledore, The Weasleys, Death Eaters/Voldemort)