What is a person who shifts allegiance from one loyalty or ideal to another called?

There were at least two allied turncoats who defected to Germany during WWII. 1. Andrey Vlasov: A celebrated Soviet general in the early stages of World War II, Vlasov became a traitor to his country after being captured by the Germans in 1942. He formed the Russian Liberation Army, a force of Soviet defectors who fought alongside the Nazis against the USSR. 2. Martin James Monti: The only known American military officer to defect to the Axis powers in World War II, Monti stole a P-38 Lightning and flew it to a German airfield, where he requested political asylum. Both would soon realize their mistake when Germany lost.

You can never relax around a turncoat.

seen plenty of these types of people in my life!!

Learned while watching a very good docudrama on George Washington, turncoat got coined when Benedict Arnold switched to fight for Britain.