Lol, this reminds me of a battle where I was in BLU team, in a payload map (I think I was a Medic too), and we were going forwards with no RED on sight. One of my teammates asked in chat "Uh....RED? You there?" We were so confused XD, and I'm pretty sure everyone in my team was like RED in this pic. Oh, and RED were hiding with 100 sentries level 3 for us.
In my headcanon, this was their very first day working together.
Heavy: DOKTOR IS STUPID! VERY STUPID MAN! Medic: NEIN! HEAVY HAS HALF A BRAIN! Heavy: I SAY, MEDIC, CHARGE ME! AND YOU WASTE IT ON DEMOMAN! Medic: NO! YOU JUST STAYED BACK AND ATE YOUR DALOKOHS BAR, WHILE ALL THE TEAM DIED! RED Team: ( Who ship this for some very weird reason, even I don't know why.) Cool, sexual tension!