Gammy

A person who force/trick/place themselves into important positions in people's lives (family, friends, acquaintances, etc.) to manipulate, take advantage of, or hurt others for personal gain or spite.

Gampa (male), Gamma (female), Gammy (child), Gam (non-binary)

I truly thought they cared about me, turns out they are just a Gampa/Gamma/Gam/Gammy.

Gampa (male); Gamma (female); Gam (non-binary/group of people); Gammy (child)