I was thinking of the years before Harry's arrival at Hogwarts, when Slytherin won the House and Quidditch cups several times in a row...
Third Snapecase entry
Media: Pentel brush pen and several Copic Multiliners on A5-size Winsor & Newton sketch paper. The greys were done with a Tombow marker and two Faber-Castell PITT pens. Colours were done in Photoshop (watch me struggle