Double-Cross by Frederik Pohl - Revolt was brewing on Venus, led by the descendant of the first Earthmen to land. Svan was the leader making the final plans—plotting them a bit too well.
The Officer of the Deck was pleased as he returned to the main lock. There was no reason why everything shouldn't have been functioning perfectly, of course, but he was pleased to have it confirmed, all the same. The Executive Officer was moodily smoking a cigarette in the open lock, staring out over the dank Venusian terrain at the native town. He turned.
"Everything shipshape, I take it!" he commented.
The OD nodded. "I'll have a blank log if this keeps up," he said. "Every man accounted for except the delegation, cargo stowed, drivers ready to lift as soon as they come back."
The Exec tossed away his cigarette. "If they come back."
"Is there any question?"
The Exec shrugged. "I don't know, Lowry," he said. "This is a funny place. I don't trust the natives."
Lowry lifted his eyebrows. "Oh? But after all, they're human beings, just like us—"
"Not any more. Four or five generations ago they were. Lord, they don't even look human any more. Those white, flabby skins—I don't like them."
"Acclimation," Lowry said scientifically. "They had to acclimate themselves to Venus's climate. They're friendly enough."