The closest word I can think of is a sycophant but that’s too strong word and not exactly what I’m looking for. The word I’m thinking of has negative connotations and it’s for someone who is friends with different groups but only at a superficial level and isn’t necessarily honest about who all they’re friends with. This person would be seen as untrustworthy.
You all are harsh.
“A social butterfly is a slang term for a person who is socially dynamic, successful at networking, charismatic, and personally gregarious. Usually, social butterflies don’t belong to a particular group, but rather jump from one group to another.” Wikipedia
Edit: Perhaps it doesn’t answer the question because it’s not a single word. It came to mind immediately though. Maybe start there and look for synonyms?
Hmm I think it’s fine if someone is a social butterfly, they don’t have bad intentions etc. I am talking about someone who seems like you can trust them but actually they have other loyalties, I live in a place where people get arrested for supporting democracy for example
If we’re talking where consequences of their friendships get you thrown in jail, traitor is a pretty good word.
What about perfidious gadabout?
I think your focus is on the disloyalty, but really there are two aspects of your description that make it difficult to find s single word which fits well. I’m also thinking the individual isn’t necessarily disloyal, but rather loyal to an unseen cause. E.g., disingenuous. If the person is a plant, then “mole” comes to mind.
I heard them called “bats” because they flap around between different groups and are associated with darkness thus “shady”!
In the USA, one term we have for this kind of person is “poseur”.