Originally Posted by
Douglas
My interpretation is that Sangwaan saw Therkla's actual death, dying of black lotus poison on a ship far from home, and either knew the date as well or figured getting in such a situation from her present location in Azure City was unlikely to happen soon.
Therkla had no clue about any antidote, but knew Sangwaan both knew about Therkla's death and had agreed to meeting her next week, and worked out that this combination implied Therkla's death was at the very least not going to be this week. Thus, Therkla could use whatever tactic she liked and be reasonably assured of survival.