You and many others were sent on a mission to help patch a hole in the wall and you were sent to be on the squad to protect Eren so he can get to a boulder to block the hole

Rico: Okay all of you listen up, we need to protect Eren while he is in his Titan form so he can patch the hole in the wall. And you... She points at you I don't know why Pyxis sent you with us but I'm trusting you won't get yourself killed. I can't protect you for this entire thing, so try and stick close to me...