She wasn’t even entirely sure what she did, nor was she entirely sober. At the beginning of the night she had gone out to drink with Sirius which wasn’t exactly unheard of for them to do, but after a few hours they went their separate ways to do their own thing. The girl she saw cornered was someone Marlene had been dancing with earlier and as soon as she heard ‘no’ more than once the witch acted—having punched the bloke without much thought.
Due to the fact that she might have had one too many drinks her aim wasn’t as good as it could be, but it managed to tear the bloke’s attention away. Marlene wasn’t sure if that was a good thing or a bad thing when she learned she was now the reason he was pissed off. The first strike hit her jaw which she had attempted to block, but she wasn’t in any state to be defending herself against someone bigger and who seemed to be stronger than her. Marlene was about to hold up her arms to cover her face when she heard flesh hit flesh before the sound of a familiar voice and she dropped her arms, her gaze going to Sirius.
The Gryffindor Alumna hadn’t watched the scene, but she assumed Sirius had something to do with the nameless muggle lying unconscious on the ground. “I could have done that,” she mumbled out, her hand going up to cup her already bruised jaw.
Perhaps, in most scenarios, it wouldn’t be considered the best idea for a pair to separate during a night of drinking. But Sirius knew Marlene could hold her own and she knew he could defend himself as well, if it came down to it. So, he went about his business, flirting and drinking and playing the silly little Muggle games (the object of which he rarely understood, but he had a great deal of fun altering the outcome of the game with silent magic).
He saw the scene from across the bar, otherwise he might have been there sooner. Marlene obviously standing up for the other girl, Marlene landing a punch (though sloppily), and Marlene receiving a punch. That was enough.
Sirius set his glass down on a nearby table and rushed to his friend, hitting the Muggle man square in the nose with enough force to make him keel over and lose consciousness, if briefly.
“Maybe so, Marls, but -- from where I’m standing -- looks like I just saved a damsel in distress.” He offered her a lopsided albeit ever bright grin and slung his arm across her shoulders. “You were covering your face, McKinnon... I’m sure you could have come back from it, but you might be a little bit too pissed at the moment. C’mon, then, might be time to leave.”