This all starts with blue medic just starting out on the team, everybody is new to each other on both red and blue teams, and they don’t know one another very well. Blue medics first days don’t start out very well and SOME people don’t treat him very well spite him being the one who keeps them alive during battle.
Over the course of long months blue medic has set up a camera system that can see only some things from the red teams side (of course it did take him a long time to set them up because it’s on the red teams side and it would be hard not to get caught). Blue medic watches them from time to time, mainly watching red medic, his rival, seeing how he gets treated a bit better than he does, on his own team.
Blue medic becomes more and more jealous of red medic, seeing how he also has a good relationship with his heavy, blue medics envy and jealous grows more, making him want to kill red medic more and more, even if he can just respawn over and over, him also not really having a relationship with his heavy. Blue medic goes more insane, all just because he wanted a little more “love” given to him, or even a good friend.