One I'm surprised has not been suggested yet, Rei raised by Washu. I think that would have very interesting potential and imagine what a thousands of years old super genius alien might do when it comes to the NERVE and Angel situation.
Another one I think that would be funny Rei raised by Lina Inverse (dragon salve on Gendo anyone?!).
Another one I think that would be funny Rei raised by Lina Inverse (dragon salve on Gendo anyone?!).