Esther looked at Lady Tyra with a meaningful gaze, which the older woman understood. Esther wanted to help the Crown Prince but it would be impossible for her to make a move with many people around. The royal physicians were always by Prince Theron's side, and there were servants on standby inside the chamber as well. Esther would find it difficult to heal him without them noticing it.
Given their situation, those of their kind would normally refrain from using their powers in front of normal humans, even to those they trusted. It was the same case for Esther. She found it somewhat acceptable to have the Queen be aware she's not ordinary, but she didn't wish to flaunt her powers to others, as it would highly likely give away her true identity.