it was the battle between Camp Half Blood and Luke. Percy lead the fight for Camp and Luke lead his own side. You see Percy on the ground, Luke continuously punching him. Percy coughing up blood

“LUKE!!! STOP!!” You scream and push him away from Percy

Luke glares at you and picks up his sword, going to stab Percy who was still laying on the ground, but you get in front of him. Luke stabbing you instead