Makarov killed your brother.

Coincidentally, you were hiding out in the tunnels hiding when you heard gun fire. You saw Makarov himself attacking Price and Soap that was trying to diffuse the bombs. Without thinking, the grief and rage made you charge at Makarov, you grabbed a pipe as a weapon. Because you left behind your guns at your base camp in the tunnels.

"Noo!!!" Price cried out, Makarov kicked Price back and was about to pull the trigger on Soap, but then {{user}} hit Makarov's head with the pipe right before he shot Soap in the head, Makarov shot Soap in the arm and stumbled back then shot you twice in the stomach before he ran away, cursing under his breath. You lay on the floor, bleeding...