Invader by C. J. Cherryh

There'd never been a good time to tell each other much of anything: that was the trouble, wasn't it? Never a way to discuss the future, no real complaint except that he'd worked too long and given too much to the job, and he'd always known the office he'd trained for was mistress, wife, mother and sister — he couldn't talk about what he did, he couldn't offload his troubles to anybody without an equivalent security clearance, and he damn sure wasn't romantically inclined toward the Foreign Secretary.
    Time after time he'd come back wound tight as a spring and so atevi-wired he couldn't speak or think Mosphei' for the first few hours; and Barb would be the first refuge after the debriefing, someone who, unlike his relatives, never met him at the door with a list of must-dos and a catalog of family feuds. He and Barb hadn't put a load on each other, that was the whole idea of R&R, wasn't it?
    But maybe she'd been
too
good-hearted — she'd known from the start she was the refuge, the safety valve for an occasionally available and generally stressed public servant the whole human race relied on. She'd ask him no classified questions, which was almost everything he knew; she'd never met him at the door with her troubles, never complained about his job, having the sense to know that he and the job weren't ever separable.
    She'd laughed and she made him laugh — and he'd lost that without ever imagining it was threatened. That was what felt unfair. To him. Not unfair, he told himself, to Barb.
    Hell, maybe human caring was a survival disadvantage. Who knew? It sure screwed up lives.
    And where in human hell did this Paul business come from? Paul — God, Paul was so damned
dull
, so damned
safe
, a real Department man, never any interest in anything but his computers. He couldn't imagine party-loving Barb sitting in front of the television knitting while Paul was off in computerland. The whole scenario was unbelievable.
    If he'd only thought to call again, when he'd stopped by his office on the way to the airport. He'd been so anxious about the travel order, so worried about getting the computer commands in . . .
    He hoped those files he'd requested had all transferred. They'd rushed him, the car had been waiting on the street — he should have delayed to check the contents. He couldn't exactly call up Mospheira now and say, Hello, I'm planning to violate Departmental policy, and I need the files you didn't send me…
    The State Department was where actions the Foreign Office knew atevi wouldn't tolerate ran head-on into humans who wouldn't remotely understand the atevi view. The State Department refused to admit that the paidhi in the field had authority to negotiate, although it accepted his negotiations for debate; it believed since it selected the paidhiin, that the paidhi, meaning the Foreign Office, should take orders from the State Department, a small disparity in what the Treaty meant to atevi and what humans insisted was the legal reality on their side of the strait.
    Translation was going to be worrisome, even paper translation, let alone real-time dealing with the language with a raft of new concepts.
    He could make semantic mistakes. He had no Mosphei' dictionary at all, a human-language dictionary being a forbidden item on this side of the strait; the Department and a university committee even censored the entirely atevi-to-atevi dictionary and semantic/contextual reference he could take with him across the strait, since there were, in the usage of certain atevi words (in the active imagination of the committee), ways the paidhi could deliver semantic clues Mospheira didn't want in atevi hands — or minds, as the case might be — until Mospheira was sure officially that they were there.
    There was some sense behind that view — there were concepts, even nontechnological concepts, that the committee rated too risky, too culturally based, too biologically based to address in the current atevi-human context, even if