Birkin gasped, his body shuddering as Stein's hand wrapped around his cock. Instinctively, he thrust his hips upwards, whimpering and and moaning with every movement. A few moments later, he tossed his head back and released himself with a loud shout.

His head flopped back down on the bed where the scientist proceeded to come down from his high. A content smile found its way across his lips as he closed his eyes. Intense. That was the word he was looking for a few minutes ago.