Let me give a hint - you know how every time you talk to me, theres usually another guy next to me? A character whose motivations and overall personality essentially revolve around their interaction with another, possibly more interesting, character with whom they really should be on an equal standing.
Contributing to their poor image in some circles, badly-written Magical Girlfriends become Satellite Characters if not outright Satellite Love Interests with disturbing frequency.
She now writes a column for GQ magazine and a Sunday newspaper, but is better known for her television work.
Glamorous, blonde, curvaceous in all the right places and sharply funny on-screen, off-air she has a warmth entirely at odds with her deadpan Have I Got News For You delivery.
The pair married at St Peter's Church in Belsize Park, North London in front of a host of other television stars, including comedian David Baddiel and his actress wife Morwenna Banks, and former Blue Peter host Konnie Huq in 2012.
Note that not all satellite characters are friendly, though...
Some satellites are the exact opposite, full of all-consuming jealousy, rage, bitterness, vengefulness, or outright hatred, orbiting until the time is right to crash violently into the character they circle. Likely to count if the character is the Fat Girl, Black Best Friend, Pet Homosexual, Hollywood Homely, or Uncool Redhead.
Contrast The Friends Who Never Hang, where a character has developed interaction with a much larger number of characters except for one or two significant exceptions.
The romantic-only variant of this trope is Satellite Love Interest.