"Sirius!" Remus yelped as the curtain covering the rattling window were set alight for the second time that afternoon. "I'd prefer not to arrive at Hogwarts as a pile of ashes!"
Peter had long since scuttled out the compartment after the first time the curtains had caught fire, muttering something about needing the bathroom. Neither Sirius, nor James had paid him much attention as they tried to put the fire out, but the jostling of the train had ensured that the aquamenti charms they cast landed everywhere but the fire.
Sirius had been trying to charm the Bertie Bott's Every Flavour Beans into showing their flavour when they were picked up, which would help avoid the truly disgusting flavours and hopefully, in Sirius and James' opinion, plant it in the Slytherin compartment before the train reached Hogsmeade. They would have planned to put it in Snape's compartment, if Lily wasn't there too because James didn't like the possibility of Lily being caught up in the prank. Especially since she always knew it was them.
"This is clearly not working. Would you two stop, already?" Remus groaned as the fire was finally put off, by him seeing as James and Sirius had gotten distracted trying to see who could soak the other first. Remus still wasn't sure how the spell had managed to cause a fire in the first place, and wasn't sure whether he wanted to find out. Or if he would find out without burning the Hogwarts Express, despite there being enchantments against that sort of thing.
"Don't you have any faith in us, Moony?" Sirius asked, with wide-eyed innocence that was so fake that Remus snorted.
"I just think you need better back up than me for all your testing! Faith has nothing to do with it!"
"Great! Let's try again!"
Written for September Back to School Challenge: Being on the Hogwarts Express
Written for Ultimate Chocolate Frog Card Trading and Duelling Club: Bertie Bott – incorporate Bertie Bott's Beans into your story
Pokemon Journey Challenge: Charmander (fire)