Another one I thought of was an AU with a heroic female Sephiroth. In this AU, it's actually Genesis who is the antagonist of the story and does most of the atrocities that the original Sephiroth did. After Nibelheim is burned down, she is imprisoned by Deepground and held there against her will by Hojo. She later gets out with the Tsviets and leaves to find Zack and Cloud, where she saves them instead of the former dying to protect the latter.
They then join Avalanche and the story goes from there, but differently. However, throughout the game Sephiroth would be made the girl who is the second love interest for Cloud instead of Aerith, since Zack is back in her life. She even gets to be the replacement date option for Cloud. And her date would be focused on her showing her more vulnerable human side to Cloud and telling about how after all this she might want to be a normal woman.
Also since Cloud would know who he really is there wouldn't be cases of identity crisis with him or being controlled by Sephiorth, since this one is on their side.
And finally the biggest change from the game is that she replaces Aerith as the one who is killed. She would be bodyguarding Aerith while she is summoning Holy, but is attacked from behind from Genesis and killed.
