They hailed him as the Sakaarson, savior of their world. They roared every time the Hulk was victorious. He'd become Warbound having made allies with the other slaves aboard the prison ship that brought them to the capital where the Red King presided.
He wanted to go home and he'd smash whatever he had to in order to do that. The Hulk didn't expect someone to know him here so Mar Vell was a surprise to see. The emerald giant had a control disc in his chest that he couldn't get off. The disc forced him to speak more clearly but translated almost any language so Hulk could understand. "You should run. They'll make you fight too."
For the Hulk to be quiet and withdrawn like this something must have been keeping him sedated between fights. The control disc was again responsible.