In Polyamory, which is defined as the state or practice of maintaining multiple sexual and/or romantic relationships simultaneously with the full knowledge and consent of all the people involved, the term Unicorn is used to describe a bisexual person (usually though not always female) who is willing to join an existing couple, often with the presumption that this person will date and become sexually involved with both members of that couple, and not demand anything or do anything which might cause problems or inconvenience to that couple.
The unicorn will be the girlfriend to the couple. The couple is usually considered a primary relationship, while the girlfriend will be a secondary partner to both. She isn’t allowed to do anything with one member of the triad, always with both. The dyad, on the other hand, are allowed to date each other without the girlfriend. If the U-Triad doesn’t work, then the dyad will stay together, and the girlfriend will leave. It’s understood that if things don’t work out that she will willingly leave with no issues. Though the dyad may choose to incorporate elements of the girlfriend’s life into the triad, it is not uncommon for the girlfriend to incorporate more of the dyad’s life into her own.
Sometimes the unicorn is expected to not develop any emotional attachment and is strictly there for a sexual relationship (equally distributed to both members of the dyad) and/or is prescripted as a secondary. This term is used as a reminder that bi poly women are people with their own desires, needs, and pre-existing lives, and not fantasy figures or pets.
Hot Bi Babe (HBB)
In Polyamory Unicorn is also a synonym for “hot bi babe” or “HBB”, and is often considered derogatory, condescending, or ironic.
A unicorn triad is considered unequal and unfair to the girlfriend in the poly community and looked upon very negatively. The term is often used to be dismissive of a couple seen to be only superficially polyamorous. Because of the demands that this type of couple places on the woman (that she be single and not take on any additional partners, and become involved with both members of the couple equally, and often “complete” their family as a surrogate mother and housekeeper and/or breadwinner and not do anything that may threaten or disrupt the existing couple), many in the poly community call this type of woman a “unicorn”, as in mythical and not likely to be found, even though there are plenty of bipoly women around. So named because people willing to agree to such arrangements are vanishingly rare, whereas couples looking for a woman who will agree to these terms are incredibly common.
In the poly community, unicorn hunters are considered to be couples (dyads) that are looking for the HBB. They tend to be new poly couples (not always but usually). Such dyads may have specific rules that allow them to end the poly relationship, send the unicorn away, and stay together.