This Team Fortress 2 Engineer is neither RED nor BLU. The respective Engineers of both teams made him during a crisis involving Overwatch’s Talon and had him join up with Richard and his team. He still remembers his experiences from both of his original RED and BLU clones. I could go on about him, but this can explain things better than I could.
Because of his individual nature, he joined the F.N.S as Kamen Rider Construct, armed with his trusty wrench and various machines. Why the machines? Mr. Conagher, would you mind explaining it to them?