Now that I think about it, in your AmonSasa comics (I LOVE them btw, they are adorable), Amon still has both arms... BUT consider the additional angst if Amon survived but lost his arm? On one hand Kaneki is so relieved Amon is alive, but on the other hand oH No I CuT His ARM OFF! Poor Sasaki has no idea why he simultaneously feels this amount of relief and guilt towards this investigator he just met, oh no, why is he crying, this is so embarrassing... And Amon is just frozen, processing it all.
YEAHHHH When I originally drew the comic I think it slipped my mind, admittedly lol, but I've actually thought about it a lot it
I think, similar to other CCG members that had lost limbs in the Owl Operation (Juuzou, Kuroiwa), Amon would eventually be fitted with a prosthetic. Ooh, maybe when Haise and Amon first meet they shake hands, but when their hands meet and Haise stares down at them his face inexplicably falls. The inexplicable feeling of relief he'd felt (so much that he could almost cry) is suddenly swept up and replaced by guilt (also so much that he could also cry, Kaneki's putting Haise through a rollercoaster).
I'd imagine that Akira's definitely there too, and she asks Haise what's wrong, and oh, god, is he crying? He's holding Amon's hand in a death grip, Amon can't really pull away, but that probably doesn't matter since he's frozen in place anyway. On one hand oh god Haise might know something, or maybe he's making him remember, this is what the CCG was so worried about, and Akira's concerned and maybe she and Amon glance at each other worriedly, and Haise's confused but he's also shaking, it's a Mess of a "reunion"/"meeting".
Haise shakes it off, somehow, and decides to hang around with Amon for a lot of the day. When they're alone he apologizes profusely, says that he doesn't know what came over him, and Amon doesn't really know what to say, if there's anything he can say, poor guy probably just has to do his best to awkwardly reassure him LOL.
Haise probably plays it off casually from there, but he still feels a strange pinch of guilt when he looks at Amon's shoulder, or his arm. Kaneki no doubt feels awful about it, maybe one time Haise apologizes about it (for it?) to Amon. Amon is confused (and worried, about his memories) and Haise snaps out of it and says that he's not really sure why he apologized. Amon feels compelled to think that it wasn't Haise that apologized, but he also doesn't want to think about it.
Oh also some additional thoughts with Haise and Akira (First of all sidenote, someone mentioned in a reply that they were wondering if Sasaki would be mentored with Amon or Akira, I imagine he would still be paired with Akira, for a variety of reasons. Like I said while the CCG thinks Amon would be useful for 'extermination' operations, they aren't very comfortable about him and Haise getting too close, also I feel like since Amon would be promoted (he was promoted to First Class I think? in canon after his 'death') he would be busy with operations for higher ranking investigators, and Akira herself was specifically chosen in canon because of her ability to comfort Haise)
That said I think Akira, already weary, would try to keep the slight fiasco of Amon and Haise's first meeting out of discussion if possible, but one day Haise can't help but ask her about what happened to Amon's arm. Akira probably doesn't know what to answer, maybe keeps it vague, then Haise asks if it's similar to Investigator Juuzou, who lost his leg in the Owl Operation, and she has to swiftly shut him down before he can press further. It's not much, but it's a piece of a clue, something that must connect Haise and Kaneki.
Maybe Haise tries asking Kaneki about it once, though the answer isn't too different from what he says in canon ('It's my fault').
Sorry my brain runs on angst can you tell LOL, Amonhaise can be so silly but they can also be such a somber mess under the right circumstances. I think Haise would be confused and lost about it and how it makes him feel, but it would eventually become a massive tell towards his past. Ough thank you again for the banger ask :pray: