Enh. See, I know that part. But I, personally, don't super love the idea of it? I get that Gilles was a really incredible guy, and may or may not be the Green Knight, but it felt really out of nowhere that suddenly also Abhorash decided he was great too. If Abhorash was wandering around, that's one thing, but personally I felt like Bretonnia - despite the Crusades and what not - really didn't interact much with Nehekhara so much as Araby. So the Red Duke was one thing, but Gilles as well? Eh. It didn't really appeal to me all that much when I heard about it. I mean, yeah, comparing apples and oranges vs. Empire and Bretonnia on some level I guess. Sigmar became a God, Gilles maybe or maybe didn't become the Green Knight, so...yeah. Sigmar obviously had all his major accomplishments, but Gilles did too, even if he didn't also do the straight up vs. Nagash+Everchosen stuff he did unify Bretonnia and had his great battles and deeds.
It just seemed both sudden, and...odd, that Abhorash wouldn't have tried to turn Gilles or something like he did the Red Duke? I don't know. It's not like the Red Duke seemed especially good at doing anything but being a rampaging asshole, which I feel like Abhorash wasn't particularly jazzed about in general. He might have come to despise humanity and such, though, which IIRC was noted somewhere that his former idealism had turned to antipathy, but that just makes it weirder that he and Gilles had sworn any bonds of friendship or honorable conduct or anything. I would more easily believe Gilles finding Abhorash a blood-sucking, monstrous, humanity-hating monster that it would be his duty to kill or something.
Maybe there was something in the line for Abhorash, but I don't know. They built him so that he was this distant, unreachable pinnacle for so long...eh. It just feels like they threw him and Gilles together, and the way it's been communicated to me is a bit more of a 'and, uh, I guess also Abhorash is there, and Gilles is so cool, and Abhorash is so cool, that they definitely are bros in martial conduct and stuff so they'll fight together as the world ends'. When wouldn't it make more sense for, I dunno, Abhorash to go try to kill Neferata? Or Nagash? Or something like, go find Lahmia and defend it as he wish he could have so long ago? Something.
It just feels, like so much about End Times, that it was thrown together way too haphazardly and with way too little coordination than something like the End Times should have deserved.