OK, this is a thread for discussing TM fanfiction ideas.
I have a couple of things I've been thinking of, and need to flesh out. The first is a story which follows initially along the UBW route, but diverges when Shinji is killed instead of Rider, forcing Rider back into Sakura's control. My eventual intention for it is for Sakura to be forced into the war, and for it to develop such that Shirou is paired with Sakura and Rin with Archer. But, I'm not sure how to make it develop in that direction, and I could do with some help.
Another idea I had a while back (although it's admittedly been kind-of done in various places since I first had the idea) was for a story in which Zouken is somehow "purified" in the third war by some AU servant, causing him to revert to being a normal old man, and realise some of the horrible stuff he's done. He's still somewhat of a dick, but within normal magus bounds, and he's now interested in passing on his family magecraft in a normal manner rather than immortality for himself.
As a result, he raises Kariya as a magus and, since the family magic doesn't involve worm-rape, he doesn't run away like in canon, and inherits the Matou family leadership when Zouken dies (some time prior to him reaching adulthood). Even so, Aoi still marries Tokiomi, and has Sakura and Rin, but she remains close friends with Kariya (even more so than in canon). When it comes to the point where Tokiomi realises he needs someone to adopt Sakura, Kariya is the natural choice, since Aoi trusts him, he's an allied family (who needs an heir much like in canon) and he is in this timeline more conscious of the usual magus mindset (although he's still a nice guy, and cares deeply for the girls as people).
Since Zouken has brought him up to be a magus, Kariya does actually desire to pass on the family magic, and thus does take on Sakura for the benefit of the family as well as for her own benefit, and he therefore does train her as a Matou magus to some extent (which is likely to be somewhat painful). However, he also loves her like he would his own daughter, and hates the fact that he is causing her pain sometimes.
As a result, whilst her training is sometimes harsh, he is always there to comfort her, and he always tries to give her a choice and to make her life generally happy, as well as making it up to her after the training by giving her rewards. Basically, he's much more of a magus than in canon and is still trying to turn her into the Matou heir or someone who will produce an heir, but unlike Zouken he genuinely cares for her well-being in the same way as Tokiomi cares for Rin's, and wants her to have a successful and ideally happy life in her own right, rather than just being a pawn for the continuation of the family.
Also, he does try to create an alliance between his family and the Tohsakas, reasoning that it's in both of their best interests, and also not wanting the sisters to be seperated more than necessary. It's likely that he would fight alongside Tokiomi in the fourth war, as allies. Tokiomi would still die, and Rin would be raised by Aoi, but it's possible that Kariya would marry her after Tokiomi's death, reuniting the sisters. If not Rin and Sakura would be very close, and Sakura would probably stay overnight at Aoi's regularly, being encouraged by Kariya to refer to her as her mother (and Rin as her sister). They would therefore go into the fifth war as allies, although they would both desire to win the Grail in their own right. Admittedly, I'm not sure where to actually take this story yet, it just seems like an interesting setting....
So, what do you think of these ideas? Any ideas on how to make them work, or what to do with them? Any ideas of your own?