He looks at Bakugou and notices him looking around nervously. And as we all know, Lukas has anxiety-anxiety which gets significantly increased when he's wolfing out-hence the need to control said anxiety. So when he sees Bakugou being anxious-he's engulfed in shadow before he can even blink
The shadows drop away, and wolf Lukas is towering over Bakugou. He looks down at him with yellow eyes, but-he's not...growling. Not yet anyway. He just looks scared...
And then he sees that Baku's scared. Scared of HIM. And that fuckin' snaps him. He gets on all fours and pushes past Bakugou, sprinting out of the building
He snaps at him-not biting him, just snapping his jaws-and pulls away, running out the door and blinking in the sunlight, squinting. And then people see him. And the screaming starts.