Severus stepped into the fireplace in his quarters and appeared to finish the step in Grimmauld. To see the actions in the same instant you'd have said he simply walked through the floo, rather than spinning through the air from Scotland to very near the heart of London. Sirius Black and Remus Lupin did not witness the first half of this excursion, but were both privy to the seamless exit. Black, the convicted felon who never really did what he'd been accused of (but had done plenty he hadn't been), in spite of the differences between him and the man who appeared so suddenly in his family home, would have said, if asked, that he'd been gobsmacked by the sheer grace of the maneuver. Lupin, who did not have quite as many differences with the man who appeared so suddenly in his friend's family home, was slightly less stunned, but still thought it the most elegant thing he had witnessed any man do.

Before either man sitting in the living room at Grimmauld could move or think, Severus focused narrowed eyes on Lupin. "You lied to me!" He snarled.

Lupin flinched visibly, and it wasn't near enough to the Full Moon on either side for it to have been the sound that caused the twitch and tensing of his shoulders. At the least, he had an idea of why Severus had come in such a huff, if he didn't outright know. He looked guiltily away from the accusatory black gaze.

Black, who had no sense of tact, misread the situation as one that should involve him at the fore (as he misread every given situation, even when he knew what either party was talking about, which, in this case, he didn't). He addressed Severus angrily, standing in defense of his friend. "What the hell are you talking about? Get out of my house, Snivellus, you have no right to be here!"

Severus ignored him, still glaring silently at the former Defense Instructor, accusing him with the very set of his jaw and narrowing of his eyes. Black looked ready to protest his presence again, this time with actions instead of words, but Lupin finally looked up. He still looked to be wincing, but he seemed to accept what had come to pass.

"Sirius, could you…give us a moment? Severus and I have things we need to discuss privately."

"Like hell, Moony!" Black said, not turning to his friend.

Slowly, as if the sockets were rusty, Lupin's eyes moved from the vicinity of Severus' chest to the back of Black's head. "Sirius, now."

The command brooked no argument, but still the dog animagus tried, rounding on Lupin. "But, Moony, I-"

"Now, Sirius…Please."

Something in Lupin's eyes, or perhaps the way he had said please in a bereft, begging tone, had his childhood friend deflating. With a final dark sneer at their company, he trudged out of the room. As soon as the door closed, the werewolf returned his gaze to the irate Potions Master still standing by the fire.

"What's this about, Severus?"

Severus knew from the way he asked that he only wanted confirmation. Lupin was well aware of what had brought about his sudden appearance in Grimmauld. The Potions Master straightened prepared for a fight.

"You told me it was a horse, Lupin!"

Another flinch. "I'm sorry."

Severus bowed up, his spine arcing as he struggled to control his anger. He felt a lick of his magic, so well controlled since his youth, dance around him. It was the first flighty tendril that harbored a complete lashing out, something he had witnessed so many times from his students but hadn't had since he had been one himself. Except for one particular student's careless breach of his privacy, he had never felt anger as dark and terrifying as this. This wasn't simple anger, it was rage, and he could feel it burning hotly in the pit of his stomach.

"You're sorry?!" He queried, almost shouting. "You purposefully hid the truth from me! You let me believe that he wasn't…" He didn't finish. He didn't know how to finish, had no idea of where the sentence had intended to go. Some glimmer of it lay hidden in the depths of his mind, but it slithered away before he could grab hold.

"Would it have made any difference if you had known?" Lupin asked calmly.

"You know that it would have!" Severus cried. He knew the timbre of his voice was rising, but he couldn't seem to help it.

"Why?" Lupin demanded, standing slowly. "You knew who his parents were, surely you suspected something like this."

"Of course I did, you fool! That is why I asked, when I first learned that he had produced one! And you lied to me!" Severus accused for the second time.

"Why does it matter? Why does your knowing now make any difference?" Lupin demanded again.

Severus glowered. "You know what it means, Lupin! You knew what it meant when you deliberately withheld the truth!"

"You hated him then, and you hate him now!" Lupin shouted angrily. "So why should the form his Patronus takes matter? It's a story, Severus! Like the fairy tales the Muggles tell of our World!"

"It's not!" Severus shouted back. His magic unleashed for a moment before he reeled it back in, concussing the room and sending Lupin back a step, almost toppling him backwards into the couch. Several shelves, and their contents, rattled dangerously. "There are a million examples of it, Lupin! Too many to be a coincidence! You know this to be fact, you've seen it yourself!"

Lupin groaned in frustration. "So what? That doesn't mean it holds true in every case! Look at me and Sirius! His Patronus is a dog that looks eerily like me in werewolf form, and mine is a wolf! Can't you see that this is foolishness?"

In a fit of uncontrollable rage, Severus turned and slammed his fist into the mirror hanging above the mantelpiece. It made for a poor substitute of Lupin's lying face. His magic enhanced the force, shattering the reflective glass, and the Potions Master slumped against the brick of the fireplace.

"It isn't." He murmured.

The shards of glass he'd scattered across the floor suddenly came together again in the frame, and black eyes stared wearily into repaired mirror, to the reflection of the werewolf behind him. Lupin tucked his wand back into his sleeve and stared resolutely back.

"Severus, please…why is this so important to you? We both know that Harry's Patronus doesn't have to mean a damn thing, so why do you care?" Lupin asked, his tone significantly softer than the shouting match from moments before. "It only matters if you want it to. Do you?"

Severus hesitated, unsure if it was because he didn't know the answer, or because he was afraid of the answer. "I…I don't know how I feel," He admitted. "He-he isn't what I thought he was. I find myself treading treacherous and unknown waters, Remus. I keep trying to envision the boy I'd always thought took after his arrogant prick of a father, but it doesn't fit with the man I see before me. It isn't just his defeat of the Dark Lord…something in the past two years besides that has opened my eyes and removed my blinders. God help me, but I want to go back to the way things were."

"Well, that just isn't going to happen," Remus said simply. He shrugged when Severus glowered at his reflection. "You may not like it, Severus, but it's true. It doesn't really matter to me why you've suddenly begun to see Harry for who he is, something many of us have tried to get you to do in the past; but it should matter to you. You need to figure out what it was that first drew your eyes away from the tip of your nose in regards to Harry. I suspect that, once you've figured that out, you'll find the real answer you came here for. An answer only you can provide."

Severus frowned and looked away from the reflection. "Why did you lie?"

Lupin sighed noisily. "Because I wanted you to discover who Harry was without something like that forcing you to do so. You're right, I do know that our Patronus' form tends to indicate our Soul Mate just as much as our magic's reaction to someone, and I didn't want you to think you had to change your opinion of Harry based solely on this one thing. If you'd found out back in his Third Year, you would never have known if you were really seeing him, or if you were just letting your emotions get the better of you. This way, you have a chance to understand what connects the two of you, rather than fighting it. I'm sorry I lied, but I honestly thought it was in both of your best interest."

Severus, who was not in a habit of exposing himself this much to anyone, straightened and shuttered his emotions behind his typical cold mask. "Would he know what it means, if he were to see my Patronus?" He turned on the man he could almost call a friend.

"I doubt it," Lupin answered apologetically. "He knows very little about our world, and I don't see when he would have had occasion to be told, since it's typically something wizarding parents tell their children before Hogwarts. Everyone thinks it common knowledge, so no one thinks to tell those who weren't magically raised, much like anything else not taught at Hogwarts."

"Good," Severus said succinctly. "I would ask that you don't tell him. I rarely have occasion to use my Patronus, but I would not risk his figuring it out."

"Why not?"

"Because I don't need to give him another reason to hate me. According to Minerva, he is sickeningly in love with his best friend's sister, and if he were to find out that we are…compatible, it would only increase the disdain he feels for me," Severus explained.

Remus frowned. "You don't know that. He might- Severus, you're bleeding."

The Potions Master looked at his left hand, which Remus had gestured to. The knuckles and tops of his fingers were dribbling blood from several lacerations, some possibly made worse when the glass shards were drawn from his skin thanks to the werewolf's reparo on the mirror. He drew his hand back defensively when Remus stepped towards him with his wand drawn.

"It's fine," Severus snarled.

Before Remus could argue, Severus turned to the fireplace, plucked a small handful of floo powder from the pot on the mantle, and tossed it into the crackling fire, all in a single move. He would have to floo to the Teacher's Lounge, as it was the only fireplace that allowed anyone to floo in from outside the castle besides the Headmaster's office (and only then if you were keyed to the wards as a professor). This suited him fine as he stepped into the fireplace and called his destination, since it was much closer to the Infirmary. He wouldn't admit it aloud, not even to a man he thought might be his friend, but now that he had acknowledged his hand, it smarted terribly. It was actually possible he had broken something besides the skin.