[In his anger, Firo'd forgotten his lie. Now that Crow points it out, he realizes that his reaction seems over the top for something as normal as a "hand shake". A bit. He drops his hand and looks away.]

W-well...

[He can't rationalize it without telling Crow the truth (he doesn't realize that the kid already knows), so he doesn't try to explain. His indignation at the implication that his violent behavior could be detrimental to Seto distracts him, too.]

There's no reason to be concerned for that, I'm doin' it to protect him. You don't want him to be safe?