Page 1701 - Enders_Game_Full_Book

It makes no sense, thought Virlomi.
Then she got the email from the Hegemony Minister of Colonization--Colonel Graff, that old sabeek.
I'm sure you're aware that one of our Battle School graduates, Petra Arkanian, was not returned with the others who took part with Ender Wiggin in the final battle. I am very interested in locating her, and believe she may have been transported against her will to a place within the borders of India. If you know anything about her whereabouts and present condition, could you let someone know? I'm sure you'd want someone to do the same for you.
Almost immediately there came an email from Achilles.
I'm sure you understand that because this is wartime, any attempt to convey information to someone outside the Indian military will be regarded as espionage and treason, and you will be killed forthwith.
So Achilles was definitely keeping Petra incommunicado, and cared very much that she remain hidden to outsiders.
Virlomi did not even have to think about what she would do. This had nothing to do with Indian military security. So, while she took his death threat seriously, she did not believe there was anything morally wrong with attempting to circumvent it.
She could not write directly to Colonel Graff. Nor could she send any kind of message containing any reference, however oblique, to Petra. Any email going out from Hyderabad was going to be scrutinized. And, now that Virlomi thought about it, she and the other Battle School graduates ensconced here in the Planning and Doctrine Division were only slightly more free than Petra. She could not leave the grounds. She could not have contact with anyone who was not military with a high-level security clearance.
Spies have radio equipment or dead drops, thought Virlomi. But how do you go about becoming a spy when you have no way to reach outside but writing letters, yet there's no one you can write a letter to and no way to say what you need to say without getting caught?
She might have thought of a solution on her own. But Petra simplified the process for her by coming up behind her at the drinking fountain. As Virlomi straightened up from drinking and Petra slipped in to take her place, Petra said, "I am Briseis."
And that was all.
The reference was obvious--everyone in Battle School knew the Iliad. And with Achilles being their overseer at the moment, the Briseis references was obvious. And yet it was not. Briseis had been held by someone else, and Achilles-the original one-had been furious because he felt slighted that he didn't have her. So what could she mean by saying she was Briseis?