At Durmstrang, to stay in the water in the dead of winter for over five minutes meant that you were strong. Six minutes, incredibly strong. Seven minutes, and you were invincible.
One February, Gellert had stayed in that icy water for eight minutes. He had dragged himself out to applause and cheers and warm blankets thrust around his shoulders, and they told him it was a record. But the moment Gellert was out of their sight he was vomiting into a decorative urn just outside the fourth year corridor, and later curling up on the floor of the boys' showers, letting his body thaw in the heat and steam.
Three things mattered, socially, at Durmstrang. Quidditch, swimming, and the Dark Arts. Gellert had no skill at the former, but in the latter two he had excelled. That he could hold his own alongside most of the Quidditch players when swimming laps in the lake made him popular enough; his talent for black magic made him feared and respected.
But he did not swim simply for reputation's sake, or only in competition. Some mornings--the warmer ones--after he had completed his laps, he would simply float there on his back, staring up at the grey dawn sky and relishing one of the rare moments in which his thoughts, very nearly, went still.
He was not sure what people from Roxie's time wore to swim so he simply donned a pair of trousers he did not much care for and a cotton shirt, hoping that would be sufficient.
He spotted Roxie on the edge of the lake as he approached, skipping rocks across its glassy surface, seemingly enthralled by the task. "I was never very good at that," Gellert said as he stepped up beside her, slipping his hands into his pockets and gazing out over the surface of the lake. "You seem to have a fair talent for it, though."