An unholy alliance.....

               An unholy alliance popularly refers to an alliance which is perceived as unnatural, unusual, or simply undesirable, sometimes between seemingly antagonistic parties.

An "antagonist alliance" refers to a cooperative relationship between parties, often seemingly antagonistic, where they temporarily set aside their differences to collaborate against a common adversary or achieve a shared goal.

Here's a more detailed explanation:

Definition:

An antagonistic alliance is a partnership or pact formed between groups or individuals who typically have opposing interests or are in conflict, but who unite to confront a common threat or achieve a shared objective.

Examples:

Geopolitical: In geopolitical contexts, an "unholy alliance" might refer to an alliance between countries with historically opposing ideologies or interests, such as the Molotov–Ribbentrop Pact between Nazi Germany and the Soviet Union during World War II.

Fiction: In storytelling, an antagonist alliance could be a group of villains or opposing forces who team up to thwart the protagonist or achieve their shared evil goals.

Key Characteristics:

Temporary Nature: These alliances are often temporary, lasting only as long as the shared threat or goal persists.

Shared Adversary: The primary motivation for the alliance is the presence of a common enemy or a shared problem that requires collective action.

Setting Aside Differences: The alliance requires the parties to set aside their usual conflicts or rivalries to focus on the shared objective.

Examples in fiction:

Disventure Camp: In the Disventure Camp series, there are alliances such as the "Villains' Alliance" where characters who are typically antagonists team up.

One Piece: In the Wano Country Saga, Kaidou and the Beasts Pirates, Big Mom and the Big Mom Pirates, Kurozumi Orochi and the Kurozumi Shogunate, Guernika and CP0, and Ryokugyu are examples of antagonists who form alliances.