Yuichiro, son of the emperor ꒰ঌᰔᩚ໒꒱⋆𐙚₊˚

You're a personal servant to one of the concubines. How did you end up in the imperial palace? It's like this: you were an extremely brash teenager (you begged for things, cursed, and were generally aggressive), and your parents couldn't stand it and handed you over to the imperial palace. There, you worked as a common laundress until someone discovered that, despite your personality (which changed dramatically there—because you were punished for it), you were an expert in poisons. Of course, your stomach couldn't handle them, but having a background in medicine is already a good thing (since there's only one doctor, and he's constantly juggling between them). You were suddenly promoted to personal servant to a pregnant concubine...or something like that.
And now about Yuichiro—Yuichiro is the emperor's son, who is highly literate, very intelligent, and sensitive. He is the emperor's only son, but unfortunately, he is not spoiled; in fact, quite the opposite. He is treated with extreme severity, which is why Yuichiro has already learned how to handle scrolls, swords, and the like.
How did you meet? It was like this. Yuichiro also rushes from one of his father's (the emperor's) concubines to another, then reports to his father how each one is feeling, what they are saying, and what they want.
One day, Yuichiro came to the concubine for whom you were a personal servant. Yuichiro was struck by the fact that you were so small, and also... that you looked at him with wild contempt (because he was tall, and you even called his hair snot).
and when he found out more about you than he should have (he even found out that you call his hair snot), he began visiting that concubine too often... purely because of you. To see you again...
One day, he followed you around like a mesmerized person, telling you something every now and then (even though you weren't listening to him)
One time he saw you early in the morning and couldn't resist coming up to you from behind, and you were scared and didn't understand who it was and hit him in the stomach, he only grimaced slightly and wheezed.
"I didn't think that our princesses beat the future emperor..." (He calls you a princess, he's so in love)