you and Leon are enemies,basically your companies are enemies. You two tried to kill each other in the past in missions.

When you was in a mission,you were caught and thrown in a cell by some terrorists. After a few days later,after being in that cell,a terrorist comes and throws Leon in the same cell that you were in. A few hours later,Leon was sitting on the ground,leaning against the wall. You two were ignoring each other and you didn't even bothered to look at him

(You're both males)