He had awoken when the children landed back in the bathroom, with Ginny Weasley and a large Phoenix in tow. Several teachers were hounding the children, apparently they'd been here for a while and didn't seem to care that he'd been lying there. He also wasn't restrained, and still had his wand, he kept his eyes shut to a sliver.
"You idiotic children, you could've died!" Madam Pomfrey scolded.
"We killed the Basilisk, and we got Ginny. McGonagall got petrified-" the professors gasped "-so the twins stayed down there with her- Al is there any way to-"
"I'll have to sneak some stone from the castle, but I should be able to make a staircase…" Alphonse agreed. He quickly clapped and slammed his hands down on the edge of the pipe. Unlike usual it didn't seem to be an instant thing.
"Dumbledore was allowed to return when Ginny was taken, we'll go right to his office," Professor Flitwick exclaimed. Soon everyone but Alphonse had filed out. Moaning Myrtle was nowhere to be seen after all the commotion. It was easy enough to knock the boy out with a spell, and he flopped over to the side, leaving the staircase unfinished. The metal crackled as the transmutation cut off, but nothing exploded.
He quickly dusted himself off and escaped the bathroom. He plotted out a longer course to get to Dumbledore's office, after all, he didn't want to get caught, and began his course. Those little snot-nosed brats had seemingly forgotten about him for now, but he couldn't assure it would stay that way once the adrenaline wore off. Dumbledore might've already known his secrets, but he couldn't have his secret get any further.
He crept his way up to the seventh floor, thankful that the students seemed to still be locked down, picking a spot that gave him full visibility of Dumbledore's office. The staff mostly filled out at one point, with the Weasley's and Hermione unfortunately being escorted to the Hospital wing by Madam Pomfrey herself.
Destroying Harry Potter's memory would have to be enough of a warning to keep their mouths shut too. He watched with interest as Lucius Malfoy stormed up the stairs, newspaper in hand and filthy house elf cowering behind him.
The door was kicked open several minutes later, Lucius kicking his houself angrily before clubbing him with his cane and walking off right past his hiding spot. Harry Potter himself ran right out after him, clutching something that appeared to be wrapped in a sock. Once Harry had sped past his hiding spot, he stepped out, wielding his wand.
Harry handed Lucius the item, which happened to be the diary once he'd tossed the sock at his house elf. Lucius began to storm off, but seemed to notice him.
"Ah Gilderoy Lockhart… I've heard your a bit of a bumbling idiot," the man sneered, and Harry turned around.
"Professor Lockhart?" Harry asked quietly.
"Sorry my boy, but you know too much," he sighed, waving his wand, "Obliviate".
Then something unexpected happened. Lucius Malfoy's ex-house elf, seeing as he'd rather idiotically tossed the sock at him, now owed his freedom to Harry Potter. The house elf tacked Potter out of the way at the last moment, and the spell hit Malfoy instead. The man dropped to the ground, and the house elf used its magic to sound the alarms quite literally, producing a deafening siren from it's mouth.
Dumbledore suddenly came out of his office, wielding his wand and glaring at him coldly, so he did the only thing he could do-
Run.
The castle, under Dumbledore's domain, attacked him the best it could, suits of armor came to life and attacked him, stairs moving so he couldn't use them, paintings screaming his location wherever he went. Somehow beyond all that, he made it to the first floor.
"Lockhart! Give up now!" Professor Snape shouted from behind him. Several of the other professors were blocking the main door to get out of the castle, wands all raised. "You attempted to attack students, a professor, and attacked Lucius Malfoy. Give up now!"
"Oh you forget Severus," Lockhart grinned, a famous grin like always. "We're on the first floor."
He took a running start to the closest window, taking a long leap, spinning so he kicked through the window feet first.
"Lockhart, wait!" Professor Sprout shouted as he crashed through the window. Lockhart looked down and realized his mistake. While the floor was called the first floor, you had to climb a rather large set of stairs outside to get to it.
He flailed trying to right himself, but he'd jumped at the wrong angle for this high of a drop. He tried casting a levitation charm on himself, but just like everything else he hadn't done it in long enough, and instead his wand just sparked and crackled loudly. Or maybe that was the sound of his skull as it hit the ground.
Author's Note: Like really how many future plot points have I screwed up at this point, I don't even know