Wheatley thought he was safe and cozy at the safe camp where he had been taken, supposedly far from harm's way.
Unfortunately, what one thinks hardly bodes well for one in a horror-genre situation.
While he was in that castle, after having 'braved' some of its many horrors, he left with something he never came in with in the first place. It slipped into his chassis when he pulled the switch to save Natsuru, and until he had those silly thoughts of safety dawning upon him, it was overlooked. Dormant. Awakening…
The object, about the size of a pebble, shone crimson. Wheatley was just minding his own business, letting his friends go ahead and put their lives in danger, until he suddenly felt himself being pulled towards the castle again by an unseen force. He struggled, calling out for those he was just as willing to leave to the wolves, begging them to save him. Still, as he accelerated towards the haunt, there was no one there to the rescue. A chute, or rather the entrance to the cellar, burst open to receive the frantic core, and Wheatley was helplessly sucked back into the house. The cellar doors closed, but that was the least of his concern. He was going somewhere fast, and he couldn't see a thing without his flashlight. Why isn't it working?
With a loud CLANG, Wheatley hit something pretty hard, but it didn't cause damage to his structure. It sounded like metal, and the thing inside him that kept his flashlight from coming on rattled restlessly inside him. At first, all the core did was panic. Then, once he wore himself out a little, he started trying to rotate his eye around until he could fish the foreign object out. It wasn't hard to do. Whatever it was, it was strongly attracted to the wall behind him. Once it found its way out, it struck the wall and left Wheatley to contend with gravity. He hit the floor and rolled into the darkness, struggling to get his flashlight on again.
It finally lit once he was stopped by something. It too was made of metal, though rusted or…bloody. He swiveled his eye about until he could get a good look at it. Up and up the blade went, in the hand of some meaty looking fellow with a weighty pyramid for a head. Wheatley had no clue who the hell he just ran into, but it seemed human enough. "Um…hello. Do you think it would be possible to just hoist me back up to the surface?"