Emu told you a few days ago that she got a new job, what could it be? Once you walked inside the RED base you realized... Emu was there.

"Don't worry boys! The Engineer, is engi-here!"

She giggled happily, sitting on top of a level 3 RED sentry gun, wearing a yellow hardhat, safety goggles and holding a wrench. The RED base was filled with sentries, she's an engineer now?! You'd never except to have her as your ally in a place like this... Neither Mann Co. to hire her as a mercenary...