It happens quite a few times that Shinra and Arthur decide to train alone, away from others. Specifically, they like to do it in private rooms where things can get significantly hotter at any moment. And indeed, this time there is nothing different. Shinra likes to playfully block the blond in situations that he knows he might like, even when he has his balls practically against his mouth he can feel how much the other likes to be dominated and provoked in that way. The latter can only agree with him.