Portal 2's plot partially inspired by panic

Valve has revealed that one of the key plots of Portal 2 came about when the writers realised they'd made a terrible mistake. Spoilers ahead.

Speaking at GDC Online, as reported by Gamespot, Valve writer Erik Wolpaw said the writers had quite different intentions for the sequence in which Chell carries GLaDOS around as a potato, which fell through at the last minute.

"We had envisioned it as this buddy cop thing, where you'd be together and you'd be bickering and it would be awesome," he said.

"It honest to God did not occur to us that the buddy cop thing doesn't work if one of you is quiet. It's funny now, everybody's laughing, but it was a true moment of incredible panic for us when we realized we'd painted ourselves into a corner."

The writing team scurried to compensate for the oversight by finding GLaDOS something to talk about, quickly inventing the sequence of events in which GLaDOS discovers her origin.

"We run into that a lot with the silent protagonist, even at this point," Wolpaw confessed, despite Valve's breadth of experience with its two quiet heroes - Chell and Gordon Freeman.

In discussing GLaDOS's back story, Wolpaw shot down rumours that Valve wrote and then cut a scene involving violence between Aperture founder Cave Johnson and assistant Carolyn.

"That is absolutely not true," he said. "It's insane."