Er Han

 "Even if I'm grateful for Third prince's kindness, I'll never betray my country!" - Er Han, |vol 1 chap 15; Silence Courtyard

Previously one of the Third Prince's servants, he was claimed traitor and killed.

Background
Kidnapped from his country, he was a solider of Munzhu who had 'now' worked under the Third Prince. He had always looked for a way back to his home country, but it's not easy-- and with such low ranking, there would naturally be risks.

As he boldly declares what had happened to him, An Wan mocks him; telling him how his cousin was sent to South Guilin Village and how both his mother and father could meet the same fate.

Turns out, Er Han had played a role in Long Lian's kidnapping, and in the end, after having his left arm broken, one of the mini black guards had slit his throat, killing him.