bedfellow

noun

person with whom one shares a bed
people and organizations that have mutually associated toward a common goal or purpose

Pronunciation: /ˈbɛdˌfɛloʊ/

Etymology: From Middle English bedfelawe, equivalent to bed + fellow.

One with whom one shares a bed.
“Yong budding Virgin, faire, and freſh,& ſweet, / Whether away, or whether is thy aboade? / Happy the Parents of ſo faire a childe; / Happier the man whom fauourable ſtars / A lots thee for his louely bedfellow.”
“Car[azie]. / In the day I waite on my Lady when ſhe eates, / Carry her pantophles, beare vp her trayne / Sing her aſleepe at night, and when ſhe pleaſes / I am her bedfellow. / Gaz[et]. / How? her bedfellow, / And lye with her? / Car[azie]. / Yes, and lye with her.”
An associate, often an otherwise improbable one.
“They say that "misfortune makes men acquainted with strange bedfellows". The old hereditary Whig Cabinet ministers must, no doubt, by this time have learned to feel themselves at home with strange neighbours at their elbows.”
“Certain aspects of reprint publishing are more akin to university press publishing than to any other sector of the publishing industry, but the relationships between the two frequently create unwilling bedfellows.”