The conversation continued for a bit longer until McGonagall ended it saying, "We can continue this in the morning when we are well rested and not standing in a girls' bathroom. Children, go to your dorms now." As he turned to leave, Harry supressed a smile for getting away without a lecture from the girls, Dumbledore or McGonagall over sneaking down to the Chamber.
Surprisingly, it was Sirius that brought Harry's hopes crashing down.
"Just a moment, professor," Sirius said. He turned and faced Harry. "While I agree that what you just told us was incredibly important, can I say also how incredibly stupid it was to go down there alone?" Sirius asked in a very calm voice that hid nothing about how angry the dog animagus really was.
"I had to go!" Harry protested. "Sasha wouldn't have talked to anyone else! I had to do something. I was the only one she would - or could - talk to!"
Sirius stepped up to stand a pace away from Harry. He looked Harry right in the eyes and said, "You are absolutely right. We needed her information and you were the only one on our side she could speak to." Harry started to feel a bit vindicated but then Sirius continued.
"However, nothing said you had to do it alone. That was your assumption. If something had happened down there, you would have had no back-up. We couldn't have opened the Chamber to help you even if we knew you needed help!
"You say Sasha wouldn't have talked with us in the Chamber. Did she tell you that?" In his shock, Harry could only twitch his head no. "So, you assumed it. Fine, let's assume that you were right and she wouldn't have talked with us there. What would have stopped you from taking a Crystal and a Portkey along so we could make sure you were safe? I could have waited at the bottom of the entrance with a silenced rooster to back you up if it had been a trap!
"Think about this. The basilisk has to feed. With her size, that means something substantial. We know she can move around the castle so it's not a stretch to think she hunts in the Forest. If she can get out and back that way, it is logical to say someone else, a certain parseltongue on the other side maybe, could get in that way. You could have walked merrily down there to find Voldemort and all his toadies waiting for you."
Harry was feeling a bit bewildered. He never been yelled at like this before. It was a strange experience. He'd been yelled at before, mostly by teachers or Petunia. But this was different. Sirius's words were calm and serious but it was easy to hear the emotion under them: fear, anger, and relief.
Sirius paused for a second to take a breath. No one said a word as they watched the former Azkaban captive and notorious prankster. Finally, in a calm, measured voice, the older wizard said, "Harry, I know you have never had anyone watching out for you before. And I know you are stupidly powerful for your age and even a bloody Alpha. You are even one of the most responsible and mature fifteen year-olds I have ever met. However, you cannot keep taking these stupid, Gryffindor risks! Use that brain you have and think! If you keep depending on luck and your gut to get you through everything then one day that luck will run out. Think about how I ended up being kept out of your life for eleven years. Do you want that?" Sirius maintained eye contact long enough for Harry to realize just how serious Sirius was. Harry nodded his understanding. Sirius returned the nod solemnly.
"Good. We'll talk about your punishment tomorrow once I've cooled off and the adrenalin from my fear is gone." With that, Sirius turned and walked to the door of the bathroom. However, he had one last thought before walking out followed by Remus who was smirking a bit.
"I swore to your parents that I would make sure you were raised right and had a good life. I failed them that night to keep that promise. Never again. I want Lily to know that. That way if you get yourself killed doing something stupid it will be you getting the rough side of her tongue for the next millennia and not me. Trust me, Lily makes you pay for your mistakes for a long time."
The room was silent for a bit. Harry glanced around and saw looks of smug satisfaction on Padma, Daphne, and Hermione's faces. Ron and Ernie just looked amused and glad it hadn't been them. Dumbledore did the twinkling eye thing, but it was McGonagall that caught Harry's attention. She looked… gratified.