I find the scene in the bathroom very sensual. I did not like it when Kay offers Marc's ecstasy, but even there one notices Kay's confidence in Marc. And when Kay begins to kiss him sensuously and Marc pushes him as if he were there imposing his leadership and submitting to Kay. The kisses are real, the intense caresses and the light of the perfect scene. In addition, Kay's smile of satisfaction at feeling what Marc is doing makes us understand that at that moment Kay was certain that Marc is also in love.
Before that also when they were dancing did you notice the joy and independence of Marc? Those scenes were beautiful.
What are your impressions of this scene? 
I LOVE the club scene! They are so in love, just ecstatic to be with each other when they dance and kiss. Don’t forget they are both quite drunk in those scenes, so no inhibitions, especially for Marc, it’s liberating.
I think it’s a recurring theme in the film that Kay is someone/something totally out of Marc’s comfort zone (breaking rules, smoking pot, taking drugs, skipping classes), contrast to Marc’s safe and tame home life. That’s why it’s so exhilarating for Marc when he finally gives in to his desire.
Kay knows that previous encounters that he can lure Marc to do many things
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Even though a lot have been made about Kay always takes the passive role during sex, I always see him as the “leader”, he leads Marc to do all the things they do together, he shows Marc how (from running properly to gay sex, and to some extent- how to set yourself free). Whenever Marc assumes in the active role in bed or in that bathroom in club, I always see it as his reaction to Kay’s lead.
Like an interviewer once told Max Riemelt in an interview - Kay is a powerbottom
