How beautiful and magnificent! (Oh, your drawing is quite nice, too :^)
What a too, member, erection, woody, stiffie.........
My goodness, OK, on to the rest of the drawing:
I adore the pent-up sexual tension: Harry's muscles, Severus' erect (giggle) stance, and obviously the big 'ole cocks standing at attention. You fic/caption was wonderful at setting up the scenario.