I hadn't noticed he was wearing different clothes in those two scenes - thanks! (That also explains why Nunnally is being carried in the first scene and in a wheelchair in the second.)

I've just posted the prologue to the fic (I'll do a LJ post linking to it once it actually shows up on FFN). In terms of the above, the point of divergence from canon comes during or just after the first scene - Lelouch gets murdered on the road, Suzaku fights off the assassin, and then he and Nunnally make it to their destination to find Genbu's already "committed suicide".