As he'd stared at the wall riddled with his own bullets, he realized that he couldn't just kill himself like he'd been practicing - not because he was unable, but because it meant nothing now. If he killed himself, he was just another student who died at the hands of the Americans. Whereas here, with Fisher shooting him down as he made a threatening attempt on his life, he was... still just another student who died at the hands of the Americans, but at least he could tell himself he went down fighting. He wouldn't be fighting the system, or the Americans, or anything or anyone important, but stopping to think of what could happen if he really was wrong and he stayed in America was just too much to mull.
The reason he'd decided to kill himself was because he'd failed, and not only had he failed, he'd failed in the worst way possible - by thinking he'd been succeeding all along. Oliver thought about where he could have been if he'd just thought of the mere possibility that the Americans had lied to them, and it probably would have been a quicker death, probably alongside Samuel. There was always a chance he could have thought of something new, maybe even something that didn't make him a murderer in the end, but there wasn't any time to think of it now - Oliver had long ago embraced the fact he would have to die for his former plan to succeed, and now was the time he ran full-tilt into that inevitability even when the plan no longer existed.
Which is why it had to be Fisher - he was the closest, the quickest, and the only one he knew for certain was alive, because at this point everyone else might as well have been in another universe. He didn't like Fisher, much the same way he didn't like Samuel, or Anvi, or Tiny, or Rajni, or Virgil, but he was a beggar at this point, with the usual comment about choosers to follow.
There wasn't a certainty that Fisher would pull through on his end of the bargain, but the bullet that travelled through his upper torso put that to rest.
Oliver had known pain before, but none quite like this. He was still travelling forward as he collapsed to the ground, and his body rolled across the road until he was facing the sky, like he was a handheld camera at the end of a horror movie. He looked at the sky as it radiated outwards from the chest until every nerve throbbed with fire. Breaths took centuries, twitches were knives. It was all pain, and he finally started to feel it ebb away.
Before things began to get dark, he resolved himself to get rid of his doubts. He had to believe this was the right thing to do, in much the same way he believed he was doing the right thing throughout this entire endeavour. Killing his classmates and then himself was the wrong thing to do, but forcing himself to die at Fisher's hands was the right thing to do. It had to be. It was. He'd done the right thing.
His eyes, just as hurting as the rest of him, saw Fisher from the ground. He looked at the other boy for a few moments, before choking out some words.
"Thank you."
Oliver didn't want Fisher to be the last thing he saw before he died, so he returned to the sky. It was orange, partially pink, webbing outwards from the west. He took breaths, even though they hurt, and eventually his thoughts turned back to his family. He hadn't really thought about it, but there was a chance they were all dead - it's not like Bellington was important, who cared if they had to kill a bunch of civilians? If there was an afterlife, he really hoped he didn't see his family there, no matter where he ended up.
As the blood pooled beneath Oliver's body on the ground and the last flicker of life exited his lungs, things finally seemed like they could go back to normal, as though that was a good thing after all.
M13, Oliver Davies: DECEASED