I don't remember who suggested this, but someone wanted to see Remus's interactions with Snape in regard to Lorena. Remember how he and Sirius originally thought Snape was some kind of pervert who had transferred his attention from mother to daughter? Yeah, that would be what's going on here.
When the knock sounded on his door, Remus knew who it was. He had no meetings scheduled with students tonight – he wouldn't dare. One glance out the window at the nearly-full moon reminded him of why. He couldn't risk a slip, couldn't risk a student being in here when he was about to transform, even if he was safe.
He wasn't surprised when the door opened without him having to invite the person in. Through the door swooped Severus Snape, looking just as bat-like in his teaching robes has he had in his student robes. Bat wasn't a nickname he'd gained once he started teaching, it had always been part of the repertoire. The bat-like qualities of his robes, his greasy hair, overlarge nose, lack of friends, they'd all been open targets for the Marauders back in school.
When he first came to the school, Remus had been nervous about having to rely on his old rival for the Wolfsbane Potion he needed. Part of him was scared that Snape would do something to render it inert and turn him loose upon the school. But the logical side of his mind knew that no matter what else Severus Snape was, he wasn't going to risk the safety of his students if he could help it, and that was why Remus took the goblets from him and downed them without hesitation.
When he first came to Hogwarts, he had been perfectly prepared to be civil to Snape. Friendliness was beyond both of them – Snape gave as good as he got back then – but civility could be managed, Remus had thought. No more cursing each other in the halls or mocking nicknames. They could be adults about this. If Snape could keep a polite tongue in his head, so could Remus, as much for his image as a teacher as for his own sake.
Then he saw her – Lorena Potter, the spitting image of Lily Evans. Her skin was paler, she was skinnier, and she wore glasses, but she was Lily in miniature, just as lovely, just as hot-tempered. And he'd seen the fondness on Snape's face when he looked at the girl. Remus wasn't an idiot, and he'd known Severus Snape since they were eleven even if the relationship wasn't amicable. He knew that look. He'd seen that look directed at Lily more times than he could count, and it sickened him to see it directed at her daughter now. It had shattered all his plans of civility.
"Snape," Remus greeted coldly as Snape approached his desk with the smoking goblet in hand. Snape arched an eyebrow at the greeting and smirked ever-so-slightly.
"My Remus, I see you get moody as your time of the month approaches," he replied easily, and sat the goblet down on the edge of the desk. Remus glared at him, but picked the goblet up and downed it like a shot. He gagged at the taste and some part of him wondered if Snape didn't make it taste worse than it had to on purpose.
"Thanks," Remus replied grudgingly, passing the goblet back. Snape snatched it.
"I should think so – I have better things to do that neuter you once a month," the Slytherin replied shortly, and turned on his heel, robes billowing, to stride for the door. Something about the superiority of the gesture struck Remus the wrong way and made him call out, and Snape's hand reached for the doorknob, "It's sick and twisted, you know."
Snape paused, hand on the knob, and replied calmly, "I wasn't aware that nonsensical babbling was a side effect of Wolfsbane. And such a quick reaction, too."
Remus leaned back in his chair and glared at the man in front of him. The wolf inside was growling. He might not be Harry and Lorena's godfather, but they were still pack, and he wanted to defend them against as much as he could. He should have been doing that since they were born, were he not what he was and had they not been sent off to the Muggle world.
"You couldn't get the mother, so you're lusting after the daughter now," Remus growled, his voice twisting in disgust around the word. "It's pathetic and twisted, and I don't know how anyone lets you around her."
He knew he'd scored a hit when Snape's shoulder's stiffened. The man turned, black eyes glittering with rage from between chunks of greasy hair. Rage fairly radiated from the man as he stared Remus down, teeth grit together, fists clenched.
"You think," Snape hissed, his voice venomous and promising at the very least a verbal thrashing, if not a physical one, "that I feel anything like what I felt for Lily for her daughter?" His sneer could have curdled milk. "I think you're the twisted one here, wolf."
"It's obvious!" Remus countered, rising to his feet and striding around his desk so that they could face each other down properly. "The way you look at her… it makes me sick."
"The way I look at her?" Snape scoffed. "You sound like some kind of romance novel." The smirk was back. "But have you ever considered how she looks at me?" Snape took a step forwards, commanding the room. "That girl adores me from the bottom of her heart," he said smugly. "She comes to me about anything, gets detention just to spend time with me. She would do anything I ask her to. I've spent the better part of two and a half years getting her trust, and you? You're nothing to her but this year's flavor of Defense professor."
Remus saw red. Snape had always been very good at digging into a person's heart and figuring out just what barbs would drive deepest and hook into the tender places inside, and he'd picked a good one. If not for Voldemort, the man Snape had served until his death, he might have been Uncle Remus, who babysat while Lily and James went out on dates. He might have been Uncle Remus who showed up at Christmas with gifts. He might have been Uncle Remus, who cheered the twins on during their first Quidditch game, because nothing could have kept him away.
Remus swung, his fist hitting flesh, and Snape's head cracked to the side. Remus froze, shocked with himself. He'd never been a person to lash out physically unless he was transform, but Snape's aim at his soft underbelly was true and, like any wounded animal, he'd lashed out. Remus stared in faint horror as Snape slowly turned his head to face forward again, a bright red spot on his jaw and a split in his lip. With a surprising amount of disdain for a man who'd just been slugged in the jaw, Snape spat a glob of blood onto the floor by Remus's feet.
"I have never touched that girl," he pronounced carefully. "And I never would. Perhaps, Lupin, you're the one we should keep her away from."
And with that Snape turned and stormed from the room, leaving Remus to collapse against his desk wearily and realize that maybe, just maybe, Snape wasn't too far off the mark on that one.