The older of the Shadow Guards was named Alex; he was an orphan who was selected by the General at the age of thirteen and trained to serve the Empire.
The younger was Caspian. Though he came from an outer branch of a noble family, he chose to join the army rather than politics. Both of them were very loyal to their kingdom, which was why Snow found them to be the perfect candidates to protect the princess.
They'd been serving the Empire for years, but this was the first time they were interacting directly with members of the royal family. Before entering the palace, they heard rumours about the King and Princess. The princess was said to be unruly, roguish, and obsessed with physical appearance. Once she saw something she liked, she would do whatever it took to get it.