User blog comment:CoGreen2.0/Billy The Intern Bash Blog/@comment-32402536-20150816164515/@comment-5221692-20150818192246

If you rewatch that scene, you'll notice that he's running away without looking where he's going. That's how he falls into the toxic pit and mutates and flies off.

What was he running from? The answer is all too clear.

BILLY!