Had another idea where 10.5 doesn't exist. Instead of him being grown from the hand, turns out to be Eight. He has no memory of the Time War, of Rose, of anything after the 1996 movie. Naturally Ten and Eight are going to clash, a sort of what if things were different.
Trying to decide how things will change and if 8.5 will commit genocide, if Ten is the one that does it.
Though on some fanfic I have read, Rose is immortal, like Jack. The Doctor of the Zepplin!verse discovers very strange readings when he discovers Rose. Turns out, aliens are attracted to Earth more these days because of the vortex energy contained in Rose. This is after 10.5 was left on the beach. I don't hate 10.5, he has so MUCH potential, but for the story, turns out he's the Valeyard and believes he has no use for Rose but he wasn't about to let Ten have a happy ending. Eight of course asks Rose to come with him after she loses her job at Torchwood because they don't view her as human anymore.
Rose is sucked into The Void and finds out that The Void isn't what the Time Lords thought it was. She wakes up in what looks like a hospital, on a ship where time and space are meaningless. Before she can go home, she meets various people who have been displaced from their reality, refugees. She meets a woman called Cypher, another called Saxon (Master!Lucy offspring), a teen named Aldric, Alt!Jack, Alt!Gwen,Alt!Ianto, Alt!Toshiko, & a group of survivors of Gallifrey called the Outsiders. Turns out the parallel version of the Torchwood group, their reality was destroyed, it no longer exists. Aldric was rescued before the ship he was on blew up. Saxon is a blond 68% Gallifreyan. Turns out, when a Human and a Gallifreyan mate, the child can be anywhere from 50% to 98% Gallifreyan, it's written in their genetic code. By the end of it, Rose does get home to her Doctor.