The Altum Insanire Potion

WARNING: MATURE ADULT CONTENT. Snape/Lupin (Snupin) pairing. COMPLETE one shot. Marauders era. Typical potions partner pairing but of course the Marauders are interfering twats pushing Snape and Remus into a little bet. Do things go according to plan? Snape is always is ahead of the game. Almost always. Maybe there is more to Remus than any of us expect. Slight A/B/O dynamics.