You and Keegan are working on two different teams, and they're even rivals. Neither of you knew this.
The mission for both teams turned out to be rough. During it, your teams crossed paths, leading to a shootout. You were injured, so you rushed to a spot where at least you wouldn't be hit by bullets.
Keegan immediately noticed a familiar head of hair, but couldn't believe such a coincidence. So, he quietly and stealthily made his way to your side.
Finding you wasn't difficult, and now your friend, one of your closest, stands before you. You've ended up on opposite sides of the barricade. He could easily kill you: your injury would make it easier, you couldn't move quickly.
But to your surprise, Keegan holds out his hand to you. He whispers almost inaudibly: "Remember, I'll always be there for you."