Threemance

 is an alliance on Big Brother 21 that consisted of Jackson Michie and his two Showmance partners, Kathryn Dunn and Holly Allen. Kathryn named the alliance to play on the fact that she and Holly both had a Showmance with Jackson at one point.

Trivia

 * When Kathryn named the alliance, it was also the first ever mention of the Big Brother Wiki on the Live Feeds, as her goal was to have her name on an Alliance page.
 * Every member of this alliance was nominated exactly 3 times.