Harry did not encounter Ron or Hermione on his way back to the drawing room, something he was extremely thankful for. Although he knew that Sirius had tried his best, Harry knew his hair was beyond repair. There was nothing to do now but wait for it to grow out and suffer the humiliation of it meanwhile.
And if Sirius was correct in his assumption that Kreacher had been responsible for the mess, Harry wanted to see for himself that whatever the irate house elf had dropped on his head and neck was not going to do him any harm. Harry realized that his skin was not burning and his insides felt quite spiffy for the time being, but as Moody had said: constant vigilance.
As soon as Harry knelt on the ground in front of the shelf he spotted a small bottle that had rolled under the nearest armchair. Harry picked it up and grimaced in disgust as he read the label.
100% Medicinal Dragon Pus Collected on the Solstice
The bottle was still half full, and as Harry rose he spotted the cork on the top shelf. He secured the top and wiped the outside with his discarded rag. Harry stuck it in his pocket and headed back to the bathroom where Sirius had conjured up a pillow earlier and was currently attempting to simultaneously nap in the tub and avoid Mrs. Weasley.
Harry stopped as he reached the hallway; sure that he had heard the familiar voice of one of his least favorite people in the world.
Snape's visits to Grimmauld Place were always short and unpleasant, but Harry and the others were on a constant quest for information since the members of the Order refused to tell them anything of substance. If Snape was in the house, he was most likely relaying a message from Dumbledore.
Harry snuck out into the hallway and up the stairs just in time to avoid Mrs. Weasley and Snape as they came up from the kitchen.
"Of course," Mrs. Weasley was saying politely as she trailed after Snape, "That you for letting us know. Would you like to stay for dinner?"
"As tempting as that sounds, I will have to pass." Snape replied with his customary sneer. "I do have a matter to address with Black, however, and I can't imagine he is doing anything too important right now."
Harry knew nothing good could come from a conversation between those two, and thought it was perhaps best if they did not find Sirius. In any case, he wanted to hear what Snape might have to say to Sirius. All he had to do was run to the bedroom and get his invisibility cloak.
"Sirius…? Well, I think he was helping Harry with something, but…"
Harry did not hear the rest of Mrs. Weasley's sentence as he dashed off and returned a minute later under the cloak. As long as he was quiet, he could look directly at them over the banister at them with no one being the wiser. Except for Moody, perhaps, who was not at headquarters.
Much to Harry's dismay, Sirius had evidently heard Snape's arrival as well and when Harry came back, was already standing in the hall and facing Snape. Mrs. Weasley excused herself and headed back down to the kitchen, leaving Sirius and Snape alone. Harry wasn't precisely afraid for Sirius' life, but he did not trust Snape; the hatred between the two men was so strong that it easily escalated to dangerous proportions.
"You wanted to speak to me?" Sirius asked, looking only mildly irritated.
"It was hardly a matter of desiring your company, Black. Dumbledore wanted me to give you this." Snape pulled out a piece of parchment from his robes. Sirius reached out to receive it and Snape dropped it just out of his reach, looking disgustingly smug.
"Accio." Sirius summoned Dumbledore's note but did not take his eyes off of Snape. "You just can't outgrow being a git, can you?"
Snape's eyes narrowed as he said, "So, having fun, are you? Babysitting Potter? I'm glad the Order finally found a use for you, seeing as you can do nothing of real value."
"I do what I can," replied Sirius coldly, "Dumbledore already has you as Voldemort's lapdog so yes, that leaves me a certain amount of free time to spend with my godson."
"No doubt," sneered Snape, "you have already asked Dumbledore for permission to return to Hogwarts with him. Perhaps the two of you can drop a dungbomb in the Dungeons or charm all the Slytherin's cauldrons to explode when they stir counterclockwise."
"What's your point?" Sirius snapped.
"Azkaban really addled your mind, Black. It is pathetic that you cannot distinguish your best friend from his son even after one has been dead for so long."
Harry saw, as he was sure Snape had too, that Sirius had tightened his grip on his wand which was still in his pocket. "I can't imagine that you have anything important to say to me anymore, so please be on your way. And don't forget that however I treat Harry is none of your concern."
"It concerns me," hissed Snape, "when he struts around the school, breaking rules just because he can and because you have given him the mistaken impression that he should aspire to be like his worthless father."
Harry's grip on his wand tightened as he saw Sirius whip out his own wand and take a step toward Snape.
"Look here, Snivellus," Sirius said in a low threatening voice. "James wouldn't want me to waste my time on such a pathetic excuse for a human being like you. He's dead and there's nothing you can say that will disturb his memory, but Harry is an entirely different matter. It's my job to protect him, especially from you. And if you so much as think about giving him a hard time, I will deal with you myself, Dumbledore's orders be damned!"
"Brave words indeed!" Snape spat, "Trying to play the parent, are you? It doesn't suit you at all, Black. I daresay, you probably hate having gotten saddled with that brat as much as I do."
Harry's stomach clenched as Sirius lowered his wand. Could Snape have hit the nail on the head? Did Sirius resent that it was he, Harry, who lived and not James? Much to Harry's dismay, Sirius did not speak for nearly a minute, only staring at a triumphant looking Snape.
"You're pathetic." Sirius' calm voice finally broke the silence and surprised Harry almost as much as it did Snape. "Harry got to Hogwarts with no idea of who you were, no memories of his father, and absolutely no knowledge of the history between you two. You don't hate him because he's actually done anything to you, you just can't get over how much of a failure you were, compared to James!"
Snape looked absolutely livid now, his wand pointed at Sirius' chest. "I could kill you right now if I wanted to. Do you think your precious godson would cry for you, or does he not love you enough?"
Harry pointed his wand at Snape, ready to interfere but Sirius did not even flinch. "When I was living in a cave last year Harry sent me regular food packages so I wouldn't have to live off rats. Would Voldemort do that for you?"
Harry had never realized how much those food packages had meant to Sirius. He felt a sudden surge of pride completely unrelated to his own perception of himself. Harry slipped the bottle of pus out of his pocket and quietly removed the cork, maneuvering the bottle out from under the cloak. Harry knelt down and set the bottle quietly between the bars of the banister.
Still pointing the wand at Sirius, Snape moved back slightly, ending up directly under the banister; Harry took his chance and nudged the bottle forward. It fell as if in slow motion. Sirius saw it first, his eyes flickered up to where Harry was, and a curious smile came over his features for a second before he jumped back.
Snape reacted on instinct. He blasted the bottle with a flick of his wand, but freed the thick contents, of which a large part came to rest on his head and robes. Harry threw himself back to avoid the blast, which turned out to be a smart move because Snape instantly swung back and pointed at where Harry had been.
"Stupefy!"
Sirius laughed. "I would rather you didn't start throwing curses all over my house. I have a renegade house elf, but he's hardly a threat to you."
"Don't think I don't know it's Potter!" Snape snarled.
"Leave him out of this," warned Sirius.
Snape opened his mouth, whether to speak or to curse Sirius, Harry did not know as he was interrupted by Lupin's voice calling from downstairs, "Sirius?" and soft footsteps coming up the stairs.
Snape lowered his wand but did not step away.
Remus walked into the hall and looked at both men, a look of comprehension entering his eyes.
"There you are, Sirius. I had a question for you. Good afternoon, Severus. Are you staying for dinner?" Lupin asked pleasantly.
Snape scowled and stepped back.
"You are becoming soft, Black, and it will cost you."
Sirius ignored his comment. "Harry isn't alone anymore, and it would serve you well to remember that."
Snape threw them both a look of utmost loathing. "Like father, like son. I will not be surprised if he comes to a bad end." And without a backward glance, he was gone.
"What was that about a renegade house elf?" Lupin asked.
Sirius smiled and accompanied Lupin back down to the kitchen, but his voice drifted up to Harry. "I don't know, it might just be a bald midget…"