Being the least favorite concubine is a surprisingly good hook

Wasn't sure what to expect going in, four years of being ignored in a garden somewhere in a palace felt like a strange starting point, and there's a real risk with a premise like this of just sitting in stagnant silence for a while, which does happen some — the formal speech and reserved distance are played completely straight without any quick softening — but if you're patient with how slowly he actually starts noticing you exist, genuinely patient, the payoff when he registers you as anything other than background does land, so buried in all that cold formality there's a decent slow burn worth sticking with.