One person, alone, who enjoys one other persons talents enough to want to form a friendship, or relationship, with them.
When plural, may be used as groupie, for supporting a group, or supporting AS a group.
W:I think you are my groupie.
J: I am not a group, and neither are you.
W: Well, no. So what are you then?
J: I'm an only.
biggest, coolest, most important, worst, any extremety.
"we were making brownies and we made the only mess."