The next day, after he does his work, he finds his room empty, presumes that the twins-six-years-apart are in Miles's room, and he knocks perfunctorily and lets himself in.
"Look, I don't care what you—hi Ivan," says Miles.
"One, yes you do, two, scientific consensus has changed in the last thousand years, three, you've seen me do it, you clearly know that it works," says Mark. "Hi, Ivan."
"Your arguing about books has a time limit," says Ivan, "Miles, th'captain wants you at the little shindig the ambassador's hosting for the new Zoave Twilightan - Twilightian? Zoavian? Whatever the word. The new ambassador from Zoave Twilight."
"Miles wants me to be his substitute because he thinks it's going to be boring. I don't want to be his substitute, because I know it's going to be boring."
"Oh, these things aren't that bad, you make small talk, the food's always nice."
"I'm very sociably inclined. Anyway, Miles, dress greens, look sharp, it's in an hour."
"Come on, Mark, you didn't even give me a chance to make my pitch!"
"Suck it up," snorts Ivan. "I'm going to go change. But call me in if you decide to argue with a mirror."
Ivan chuckles and goes back to his own room to get into his dress uniform.
Miles changes. Reluctanctly. And appears in the hall, also reluctantly.
And he and Ivan go and meet various assistants of the Zoavian ambassador (Ivan inquires of his the demonym and she tells him that's what it is) and serve as their escorts at the party. The food's lovely.
The food is lovely. The loveliness of the food somewhat makes up for every other aspect of the situation.
There is another of the same a couple days after; this sort of event is scattered on an irregular basis between the clockwork of Ivan's day job and the as-time-allows of Ivan's out-of-the-embassy social life. Miles and Mark continue to develop rapport and are eventually moved to visit the embassy gym in addition to the endless reading-and-partially-telepathic conversations.
The Dendarii go about their business without any disasters that require elaborate Milesian shenanigans to depart the embassy and see to them in person.
Miles's money and his orders from Tau Ceti come in - he and his Dendarii are wanted elsewhere in the galaxy with all speed. Ivan bids him goodbye and proceeds about business as usual, including going with Carolyn to some kind of traditional cultural festival, which is very cultural, involves tasting a few dozen kinds of cheese, and sees him heading home via tubeway from its slightly far-flung location in the late evening.