Synkie

Synkie was one of the two twins sent by Prince Consort Werner Venetiaan from the Holy Kingdom to assassinate Jesse Venetiaan during his time as diplomatic hostage in the Riester Empire.

He is priest, and partner to his twin brother Peter, who is a Holy Knight.

Although every attendant in the Imperial Palace has to go through a rigorous check to get into the palace, Synkie and his brother Peter were able to get their hands on the checking process as well after killing the original Bellang twins while they were on their way to the palace, and stealing their identities to go through the interview.

It was theorized by the Imperial Guard that someone who works for the Bellang family received some money from the Holy Kingdom and handed over the information about the attendant candidates, which allowed for Synkie and Peter to be able to switch places with Steve and Renault and sneak into Juliette Palace as attendants.

Story
Assassins who fail their missions usually commit suicide to protect their masters. However, since Jesse used his Divine Oracle to order Synkie and Peter to not kill themselves, they were in the end arrested by the Imperial Guard. They would've been tortured for their information, had it not been for Cardinal Aurélie Boutier's powerful Divine Oracle. According to her, "It isn’t very hard for me to completely cleanse the minds of children who have lived their whole lives being brainwashed."

As for their fate following their arrest, the twins will be charged with attempted murder on a member of the Imperial family since they tried to kill a prince of a foreign nation residing at the palace. They will not be executed, however, due to the benevolence of Jesse and the Bellang couple, though they will spend the rest of their lives in prison.