Subverted: Bob appears to be winning the battle, but then comes General Drake.
Double Subverted: ...who gets swatted away in a second, only for Bob to turn back to Evulz.
Bob wears himself out several times, only for the bloodied Evulz to taunt him by saying "Is that all you've got?", pushing the newly enraged Bob to redouble his efforts.
Alternatively, Evulz appears to have been dressed as a piņata, with Bob attacking by whacking him with a stick while blindfolded.
Zig Zagged: Bob feels the urge to thrash Evulz, but he supresses it, until Evulz makes another threat and drives him to bloodlust. Halfway through the beatdown, he suddenly realizes what he's doing is ugly and unneeded, so he restrains himself again and takes Evulz into custody.
Averted: It looks as if Bob is about to go on a violent rampage and prance around in a pool of Evulz's blood, but he stops once he's got the guy restrained and incapacitated.
Lampshaded: "Uh, dude, you can stop now."
Invoked: "I'm going to make you suffer. Normally I hold myself back, but not for you."
Defied: Bob, with obvious effort, restrains himself from letting his rage take over.
"Evulz is really gonna get it now, isn't he?"
"Are we witnessing a ridiculously one-sided fight or an execution?"
Conversed: "Wow, I know he's the villain, but this is one hell of a smackdown he's getting. It's...kind of scary, to be honest."
Deconstructed: The adrenaline wears off and Bob stops due to his agonizing fists; he finds himself disgusted at what he's done to another human being, realizing that Evulz will die from his injuries and that the extent of the brutality he inflicted will lead any jury to convict him of murder.
Reconstructed: Evulz, who'd been threatening a helpless innocent, was so genuinely deserving that people are willing to forgive Bob's use of excessive force.
Evulz is trying to break Bob's Thou Shall Not Kill policy, by constantly attacking Bob and threatening his loved ones, no matter how bad a beating. Bob is forced to beat Evulz into a bloody broken mess before he realizes this is just what Evulz wants.