In Metal Gear Solid 2: Sons of Liberty, you're introduced to Emma Emmrick, the younger stepsister of Hal 'Otakon' Emmrick. You find Emma in a very similar way to finding Otakon, complete with wetting herself in a locker. You need her help in the computer room. It's a good thing she's able to run and swim. Wait, no she's not. She's not able to move her legs and she's aquaphobic. Well, this sucks.

Not only does she hold on to you as you try to swim underwater while freaking out, causing you to take extra stops along the way so she can catch her breath, you also need to keep her alive from enemy fire. After you get past the swimming portion, she's basically a human slug, dragging herself while you have to protect her from enemy fire. Plenty of games have 'protect the weakling' mission, but protecting Emma in Metal Gear Solid 2 is at the top of our list.