From
元代 Wang Shifu's drama 《
西厢记》 (Romance of the Western Chamber), where
红娘 is the clever maidservant who sneaks her mistress
崔莺莺 Cui Yingying together with the scholar
张生 Zhang Sheng. Her name became the generic term for matchmaker — much like 'Cupid' in English. Now extended to any go-between, including business
红娘.