Harry had to stay in St Mungo's for another 3 days after the incident, but he got Predawn back with relative speed, which seemed to help him, at the very least it settled his magic and helped to ground him better than he could when he had sensed they were in trouble.
"Massssster!!" Predawn said, sounding like they were sobbing as they curled themself around Harry immediately after being brought into the room by Remus who was clearly still a little uncomfortable holding the snake.
"Predawn!" Harry hissed back, glad to have them back, he had gotten better magically and physically, but he had been worried about Predawn since he had lost contact with them.
"Masssster, I'm ssssssssorry, I went exxxxxploring without permissssssion." Predawn hissed, tilting their head down in shame.
"Harry, could you ask where Predawn was, it could help everyone to find the Basalisk and deal with the situation." Remus asked, sitting on the edge of the bed. At the moment it was only him, Harry, and Predawn in the room. Draco would perfectly happily have spent the nights at St Mungo's with him, but, unfortunately that wasn't allowed, although it was fairly obvious that Narcissa was actually glad, she wasn't too fond of spending much time in St Mungo's or any other healing facility, that's part of the reason the Malfoys employed a private healer. Sirius was helping the teachers of Hogwarts arrange a way to keep caring for the students with such short notice.
"Predawn, where were you? and how did you get there?" Harry hissed at the snake that was wrapping and unwrapping itself around Harry's waist.
"They called it The Chamber Of Ssssssssssecretssssssssss. It'sssssssss through a ssssssssssink in an abandoned bathroom, other than a ghosssssssst. You need our tongue to get in." Predawn hissed, proud of themself for being able to find the hidden area of the castle, almost seeming to have forgotten what had happened thanks to the exploring.
"Predawn said it's called The Chamber of Secrets." Harry said quietly to Remus, the man only vaguely aware the other two were talking from the low hissing that was only audible if you really focused on it, thanks to the telepathic nature of most Parseltongue.
"The Chamber of Secrets? I thought that was just a myth. How did they get in?" Remus said, a little shocked, but having no reason to disbelieve Harry's words, after all, it didn't seem like Harry was really aware of the myth of the Chamber of Secrets, it was one that while vivid had ended up dying out, especially among Slytherins due to other houses immediately suspecting anyone from Slytherin who started talking about it.
"Predawn said you need Parseltongue to get in, but it's a bathroom on the second floor which people don't use but there's a ghost." Harry relayed the information he had.
It was with great difficulty that Remus didn't swear, of course the mythical Slytherin hidden room would need Parseltongue to get in, the only problem is the only known Parselmouths were Voldemort and Harry, and there was no chance Voldemort would help them, if he was even alive or sentient, who knew what happened to him after last year, but did that mean he was supposed to send Harry back into danger? The best place to attack the Basalisk would be in its den, where it's likely Predawn had been, as there would be less splitting up required and that would, in turn, make it easier to take anyone petrified out again after the situation is over.
"Do they know which ghost it is?" Remus asked, trying to force himself to seem calm for Harry.
"What wassssss the ghossssst called?" Harry asked Predawn, the twitch of Remus' ears the only sign of any discomfort or hearing of the Parseltongue.
"I don't know, they were alwayssssssssss crying in the pipessssssssssssss." Predawn hissed back, getting comfortable over Harry's shoulders.
"They don't, but the ghost is always crying in the pipes, according to them." Harry told Remus in a whisper.
"Okay, I think I'll be able to figure out where that is. Thank you both for your help, Get some more rest, the Malfoys should be here this afternoon." Remus said, pressing a gently kiss to Harry's hairline as he got up to leave.
-----
"Fuck!" Remus yelled at the top of his lungs as he got back home, making Sirius almost jump out of his skin, not hearing the flu blaze up as Remus was spat out.
"And you call me dramatic, what happened?" Sirius replied coolly, although he was obviously joking from the slight mischievous twinkle in his eye.
"I got Harry to ask Predawn where he was and how to get there. It's the bloody Chamber of Secrets, oh, and you need to speak Parseltongue to get in." Remus spat with anger, pulling on all the strength he could muster to not punch a hole in the wall.
"Well shit." Sirius said in response, not used to being the calm one, but only too aware that someone needed to be. Last time there wasn't a calm, level headed one, James had to risk his life to save Snivilus of all people. "Do you at least know where the entrance is?"
"Most likely Moaning Myrtle's bathroom, I wouldn't be surprised if it turned out she died because of the Basalisk's previous outings." Remus said, bitterly, fighting his aggressive frustration as much as he could.
"First thing's first, we tell Natasha McGonagall-"
"Do you have to use her full name?"
"I don't know what else to call her. Anyway, first thing's first we need to let Natasha McGonagall know what Harry told you, then we should go talk to Lily and Prongs to help calm you down, then we can all brainstorm how to deal with this without throwing Harry back into danger." Sirius said calmly, doing a surprisingly good job of not being dramatic or joking around, probably from having learnt from Remus, Lily and James for years. "Do you need a calming draught or can you wait for me to fire call Hogwarts and we can go to the Potters'?"
"I'm fine." Remus said, sagging a little, covering his eyes with a hand. His wolf, much as he despised that part of him for years, had clearly accepted Harry as his cub, making it that much harder for him to deal with what Harry had gone through, even though he's supposed to be one of the adults in charge.
While the Wolfsbane potion did wonders for full moons, allowing him to keep his sanity and be pretty much a large, friendly dog that didn't need multiple animagi keeping him in check, it also had an effect on the wold all month round, making it itch away under the surface, waiting for a moment of weakness to try to come out. Of course, unless it was a full moon, it was impossible to transform, but the eyes would change and they could loose some control and become more violent than they naturally were.
"Okay, I'll make the call now, get ready to leave." Sirius called, heading to the fireplace.