Harry Potter and The Twilight Saga
9 parts Ongoing What if Bella had a twin sister from a God? What if Renee and Charlie were wizards? Charlie a Pureblood and Renee a Muggleborn, Renee is Lily's twin sister, and was originally named Rose Evans, but when Lily and her family went into hiding, so did she. She changed her name to Renee Higgenbottom.
What if, one of Hermione Granger's parents was a squib instead of just a Muggle? and Hermione also had a twin sister whom was a demigod as well?
Meet Melody Anna Swan and Cassandra Ann Granger both demigod/witches, Isabella Swan and Hermione Granger are both Halfbloods
Disclaimer: I own nothing but the idea, Melody Swan, Vivian Stanley, and Cassandra Granger.