[Knives is doing the same thing, making sure to fit in 'brother' as much as possible to ensure the familial relationship is firmly established. He doesn't even want to think about putting his brother in that kind of situation, and he doesn't think that an argument is worth that sort of punishment.

He trails a hand over Vash's shoulder before pulling away to get the gag. He had said that the symbolism of gagging him would play well with the crowd.

He brings it back to Vash.]

First thing first, little brother, we'll gag up that wicked tongue of yours so these good people don't have to listen to your offensive voice.