The real traitor is Samara

Person with whom you start watching a series and keep watching the episodes without you.

Someone who continually goes back to a toxic ex. This person will burn every single bridge around them. They throw anyone under the bus who stands between them and their selfish ways. *A Backstabber

A person who is not loyal or stops being loyal to their own country, social class, beliefs, etc.:

A black conservative

When someone leaves your Krunker group to play No Man's Sky

Traitors betray their friends or presumed loved ones and their trust, from small betrayals to large ones.