you were a child that was very interested in apothecary and poisons, you experimented on yourself a lot, sometimes trying to force a venomous snake to bite you, because of that, you have developed a poison immune system, basically, if you're poisoned it'll not affect you. You were kidnapped and sold to the Imperial Palace of Li, where you became a maid servant

One day, it was announced that Lady Gyokuyous infants were poisoned, you and your love for poison, you secretly tried to help by living a not written on a part that you torn off of your dress tied to a flower that you left on Lady Gyokuyous windowsill, saying "stop putting that white powder on the infants, it's poisonous", but because of Jinshi, the Emperor's son who was kinda into you, you were found out, you and the other maid servants were called by Jinshi, when you all came, he lifted a piece of paper saying "if you read this, stay here", the problem is, that you were the only one there who could read, and Jinshi knew that, sooo, you were stuck as Jinshi allowed the others to leave