It takes him two months to lose his accent. He takes some of it back after he discovers it only draws more attention. Everyone knows he's Komarran. It's more conspicuous if he blends in too well. It's better to look as if he's trying, not succeeding.
He'd chosen the accent he was most familiar with, the sharp one out of ImpSec propaganda, and he learns to soften it. Komarrans know Barrayarans from their works, but Barrayarans know themselves from their neighbors. They expect and trust the familiar; Duv learns to give it to them. He plays with it, watching their reactions to him change as it fades in and out, watches how they respond. He watches the Komarrans, too, and they watch him. Some try to fit in, others take pride in always standing out. Duv knows better than to look like he's a proud Komarran. Proud Komarrans stay on Komarr. Proud Komarrans know the only thing to learn from the invaders is how to grind an invading force down until they retreat. Duv's no guerrilla, not anymore.
After a year on Barrayar, he talks like a Komarran who's gone native. He fits in, as much as he ever will.