我若是妃谁便是王你若是妃我便是王
[wŏ ruò shì fēi shéi biàn shì wáng nĭ ruò shì fēi wŏ biàn shì wáng]
If you were an empress consort ('fei'), I would be emperor, or vice versa—connoting a relationship dynamic suggesting mutual dominance or royalty-level importance to each other.