The Pureblood Mudblood Muggle

Cathy Holt was perfectly happy with her life, thank you very much. She is studying to be a surgeon, has a nice steady relationship going and is living quite happily. Then she dies. The end. Of course, that isn't what happened. Instead, she wakes up as a baby. And her older sister is some snotty kid called Petunia Evans...wait a minute. Little Petunia Dursley? Oh she is screwed