Tugboat

[Dianne]

An un-attractive girl that attractive girls often surround themselves with.
The [mutually beneficial] arrangement allows the attractive girl to have menial tasks performed for her, and make herself look more beautiful by comparison. The unattractive companion(s) get to pick up the higher [quality male] scraps the attractive girl draws in.
Named after a long, graceful ocean [liner] surrounded by several ugly, short, tugboats as she enters harbor.

[Cami]

a boat with a powerful engine which can change direction easily and is used to pull large ships into and out of port

[Marquetta]

A powerful boat used for towing larger vessels, especially in harbor.