Marcus was a little worried about the shambling dead they caught glimpses of in other hallways, worried about leaving enemies at their back, but it wasn't like they could afford to get distracted.

The gray giant apparently wanted to go into a room with some zombies in it, so Marcus remained outside the door with his gun at the ready in case any managed to get past his new ally. That didn't happen, though, the gray giant tossing them around like rag dolls before stepping forward. Marcus turned his attention to making sure nothing came down the halls behind them instead.