The term originates from Chinese fantasy web novels (玄幻小说) and games where heroes form magical contracts with powerful beasts that serve them unconditionally. Around 2025, users in China's 字母圈 (BDSM subculture communities — literally "alphabet circle," named after the BDSM acronym itself) on Douyin and Bilibili repurposed the term as coded language for real-life power-dynamic relationships, specifically the 24/7 dominance-submission model where one partner acts as the "master" and the other as their obedient "contracted beast."

The humor — and the virality — comes from the gap between the epic fantasy image and the actual meaning. Douyin creators began posting skits where someone's partner issues commands and the "contract beast" instantly complies, playing the joke completely straight with dramatic fantasy music. The term also works as a censorship workaround: platforms moderate explicit BDSM content, but fantasy-novel vocabulary flies under the radar. Related phrases like 召唤契约兽 (summon the contract beast) and 签订契约 (sign the contract) became part of the bit.