strange bedfellows

Unlikely companions or allies; often used in the phrase “politics makes strange bedfellows.”

A peculiar alliance or combination, as in George and Arthur really are strange bedfellows, sharing the same job but totally different in their views. Although strictly speaking bedfellows are persons who share a bed, like husband and wife, the term has been used figuratively since the late 1400s. This particular idiom may have been invented by Shakespeare in The Tempest (2:2), “Misery acquaints a man with strange bedfellows.” Today a common extension is politics makes strange bedfellows, meaning that politicians form peculiar associations so as to win more votes. A similar term is odd couple, a pair who share either housing or a business but are very different in most ways. This term gained currency with Neil Simon's Broadway play The Odd Couple and, even more, with the motion picture (1968) and subsequent television series based on it, contrasting housemates Felix and Oscar, one meticulously neat and obsessively punctual, the other extremely messy and casual.