The word is important for me trying to figure out which of the people I know fit that category, it's just that simple.
What's the closest thing to it?
Such a person might be described as clingy.
Via Merriam-Webster:
tending to stay very close to someone (such as a parent) for emotional support, protection, etc.
I've personally always heard the word used with a negative connotation. Example usage:
Chances are you don't have much of interest in being the clingy one in a relationship. It comes with a whole slew of negative connotations — worst of all being jealousy.