Attention
Gohan was furious. His father had come back, just for one day, and once again he was only concentrating on two things: fighting, and Vegeta. Seeing his father watching the prince, barely taking his eyes off him as the smaller fighter moved was torture. When he'd imagined seeing his father again it had been with the hope that he would be a father, just for that day, but he'd wanted Goku to come back to see his sons.
Things had been almost right before the Grand Kai showed up and escorted them off to this place. Sure, his dad had been staying with Vegeta, Krillen, Piccolo, and the other fighters rather than with his mom, but then they were fighters too and since Gohan was one of that group he didn't really mind, although he knew his mother did.
Goku had cheered for Goten, staying and paying attention even during the boring fights as the youngest Son won his matches against everyone but Trunks. When Goten lost, he hadn't seemed particularly surprised, but the look of sheer happiness on his face as Vegeta rested a hand on his shoulder in reassurance was… sickening. The prince didn't realize what it meant to him; he was only trying to be more human, and thinking of the way he would have felt if Trunks had lost, but his son did. That had been the beginning of the end.
His father hadn't stayed with him to watch Trunks' final match. It wasn't that he thought it would be interesting or that the man would enjoy it, but couldn't he at least pretend he wanted to spend time with his son. It had been seven years since he had died, after all.
And then the Grand Kai had taken them to this place and Gohan had almost been glad when Piccolo and Krillen were paralyzed once he learned it was reversible. It meant that he and his dad were almost alone. He could finally talk to him!
Nothing of the sort. Goku's attention hadn't wavered from Vegeta once the whole time. Even during Gohan's fight his father wasn't really looking at him. Vegeta paid him more attention than his father did, even if it was mostly to carp about how Gohan was getting soft and he himself could have killed the other fighter by now.
Then Vegeta was possessed and Goku had a reason to pay attention. Gohan tried to interfere, to remind him of what they were trying to do, but the bespelled prince knocked him aside. Vegeta didn't hurt him, although he could have, but he did make it clear enough that Gohan should stay out of it.
Gohan clenched his teeth. Vegeta didn't understand. He always had everyone's eyes on him. He didn't know what it was like to fight for his father's attention and lose to the man he was supposed to hate. Vegeta had all the love that Goku was supposed to give his sons, and Gohan couldn't even hate him for it. His father had always been that way.