A/N: Heyyy this fic is still alive.
Bruce prided himself on being a pretty sharp guy. It was one of the few things he could pride himself on. His struggle with his angry green passenger had cost him dearly. His career, his home, his safety, the love of his life. But he still had his intellect, still had that razor-sharp mind. The problem with a sharp mind, though, is that it can be difficult to control.
So despite knowing better, despite knowing that no good would come of it, Bruce couldn't stop churning through an endless list of what-ifs.
What if Hulk, Loki, Heimdall, and Thor had been able to work together more efficiently, tackle Thanos at once? Perhaps they could have overpowered him with their combined strength. It was that first sloppy attack that had sent Hulk cowering like a frightened dog deep into the recesses of Bruce's brain. Had ended in Thor's brother and people slaughtered before his eyes.
What if Hulk had been just a little bit braver? Could the battle have been turned in their favor with his assistance? The borrowed Hulkbuster suit was appreciated, but was far from ideal.
What if Hulk had been able to distract Thanos so Thor could land a fatal blow?
What if Peter Quill had kept his head? What if Thanos's daughter had been rescued in time? What if they had hidden Vision better?
What if, what if, what if.
Bruce didn't stick around for long after the battle, after half of what he had come to think of as his family turned to ash. To be in the backseat while Hulk took the wheel for years, to be gone for so long, and then return to this unbearable loss was too much. He slipped away while Natasha tended to Steve. Where to, he didn't know. Stark Tower was out of the question. He needed to escape. Back on earth after years on an alien planet, and he already needed to escape. Maybe somewhere in the Philippines.
They would look for him, of course. They would be worried. And they would want his help as they tried to figure out some sort of fix, some sort of solution. But there wasn't one, not to something like this. It was better this way, to peacefully slip off unnoticed. To leave while he could.
What if he knew the other guy wouldn't spit the bullet out?