If Longbottom wasn't a ridiculous plant boffin, Draco wouldn’t have purchased a bonsai from him, and Longbottom never would have mentioned him to Potter. Potter wouldn't have used him for the auror department, Draco wouldn't have met Granger, he certainly wouldn't be incarcerated in this perfumery lab, or indeed, wrapped up in any Gryffindor shenanigans at all. 