Cooper Harley, as you may have guessed, was not a particularly intelligent or thoughtful man. However, there were certain things he felt to be fundamental truths of the universe, certain things he felt were unimpeachable under even the worst of circumstances, the glue that held all that we know together. You die if you stop breathing, you bleed if you cut yourself, and you don't get held hostage if you're the only one in the room in possession of a firearm. Cooper had a feeling that some basic cosmic law was being broken here. Along with his chair. Somehow he doubted Reed would pay the homeowner for that chair. Didn't he know the Girl Scouts rule? Leave everything the way you found it? Guess not.

"Man, what the fuck! I was sitting there!" Cooper complained. His eyes widened as he heard Lillith's words. The implication. The implication made sense. A violent man confronted them for no real reason, threatened both of them for whatever scraps of information they had gathered. Of course. Had to clean house, eliminate witnesses.

"So it was you, huh?" Cooper said slowly as he pulled himself off the floor. "Pretty obvious, really. I have a hard time believing you don't care about any of this. Seems more like you're trying to cover your tracks." He realized, without any planning, that he had positioned himself between Lillith and Reed. "Besides, who'd miss a couple of drug dealers, right? You take care of them, you scratch that little itch again, you get a pat on the head from Babylon. Then maybe in a month or two, or the next full moon, you go and kill another girl, blame someone else for it. And the whole fucking cycle starts over again." Cooper sneered through his bad teeth. "You know, I'm a coward, you said it yourself. I won't deny it. But at least I have the courage to do my dirt out in the open. I don't sneak the fuck around and pretend to be a hero, cause I'm not. I'm a criminal." 

He forced himself to meet the man's eyes, despite his pounding heart and churning stomach. He very much doubted he could take Reed, even with the pistol. But if he really was a murderer, then he had to try. For Lillith's sake.

Wait, what?

That last part had somehow crept into his internal monologue, an unscripted ad-lib. Cooper had always looked at himself as pragmatically self-interested, always looking out for number one. Because that was what the bad guy did, right? Burned all his bridges.

Did he have any friends? He couldn't remember. Probably not.

But he could at least not fuck up this one thing.

"Lillith, get out of here," he said as calmly as he could. He was terrified of Reed. Cooper legitimately believed the man had killed Mari and meant to kill them. He wanted to run. He wanted to run very badly. But as long as he stood between Lillith and Reed, he would remain rooted in place like an oak and do whatever he could to keep Reed away from her. Cooper had never been smart, why start now?