I don't know if something of this sort has been attempted before, nor am I a fan of writing fan fiction in general. I'm here mostly for the discussion something like this would produce, and I thought it'd fit better in here.
Now, the idea is simple: take the Fate/Stay Night setting, take the masters, including Bazzet(is that how you write her name?), take the servants, excluding Avenger, rematch them, and then just lorewank about the outcome.
I'll begin with a recombination and a bit of theorizing.
Illya-Saber
I still wanted Illya to be a nuke, but I think it'd work very differently with Saber by her side. If she knew the outcome of the previous Grail War, or either got to know through Saber, their relationship would be very interesting. Plus, I think it'd be one of the first times Saber just gets to be used as a pure Excalibur machine gun.
Shirou-Archer
I think Archer would be interesting along Sakura as well, but I'm putting him with Shirou not only for the interactions but also for the meme. Even then, having the whole of UBW but told through the lens of cooperation, or at least some very SOB level Rule Breaking, would be rather fun.
Rin-Rider
I think Rider is one of the more strategically aligned servants of the bunch, including things such as her fighting style and her Bloodfort Andromeda. Paired with Rin, a strategy monster, I think they'd be able to cause some pretty huge damage, surely more than what Rin managed to do with Archer, I believe.
Kuzuki-Heracles
Two mute fridges of a man would be either commedical or really drab, but I put this here not only for the potential of itself, but also because it implies
Heracles-Kojiro
I don't think it's fair to change how Kojiro belongs to a servant, but I do think it's fair to change the servant. Also, having him be the servant to the Berserker could possibly bring about as strategical as a Berserker can be, either that or making Kuzuki actually have to take an active effort in planning.
Bazett-Gilgamesh
The dead girl getting the Sumerian god might actually make her not die; it would also be interesting to see how she would act alongside a servant she didn't want to bone. Plus, I wonder how Fragarach and GoB would act. I think they're also a good match since they deviate from the standard HGW in their own ways.
Sakura-Cu
Honestly, this and the next pair are the ones I see the least potential, it's mostly because I didn't want to see Cu end up with Kotomine. But still, there is some potential to be had here. Seeing Shinji get a stern talking to from Cu would be nice, especially when he's supposed to be the actual servant.
Kotomine-Caster
I feel potential and interest here, but I have no idea whatsoever how it would pan out. It'd be something to tell for sure, but I can't put my finger on it.
That's mostly it. If anybody would like to talk about different combinations or elaborate on the ones here, I'd appreciate that. Again, I don't know if this has been talked about already in here or old BL, but I wanted to take my chances anyways.