Note: This story was written as part of the "Ring of Fire" game in the Harry Potter Fanfiction Challenges forum.
Challenge:"Me, whoever picks this card must write a story using 1 prompt"
Prompts: "Are you sure? My money says differently." (chosen) & Character death (imposed)
Warnings: mention of two off-screen deaths (one human, one animal) & a blatant ignorance of how horse racing or betting actually works ... so please suspend your disbelief for the sake of this fic! :) Also un-betad. All mistakes are entirely my own, so read on with caution.

"I say we go with Buttercup."

"Are you sure? My money says differently. Say, Sassy; the odds there are way better."

"Well, it's my money , Sirius, so it doesn't matter how your money speaks."

"Oh, pulling that card, are you? Well if it hadn't been for Remus, we wouldn't have been able to convert our Galleons in the first place."

"If Remus wanted a say in this, he'd have come himself."

"Remus and I are one!"

"Well Peter would be on my side."

"Please! Peter would splinch himself in two before being made to choose sides."

James glowered at Sirius, who glowered back. They at a race track, standing inside near the betting booth, arguing over which horse to bet on.

"Look," Sirius was trying to sound calm and reasonable which struck James as a laugh since he really wasn't either of things, ever. "It doesn't matter what horse we met on, remember? We're going to win no matter what."

"Maybe so, but there is such a thing as subtlety, Pads. We don't want to bet on a horse that never wins and make ourselves look suspicious. Look at this," James pushed the DRF toward Sirius, "Buttercup's got some unexpected wins scattered over the months. The odds on her aren't great so we'll make a decent payoff and her win will put down as another unexpected performance. Sassy hasn't won a race since 1968, for crying out loud!"

"Fine," Sirius muttered. "Why do you have to be right all the time? It's bloody annoying." Grinning, James just rolled his eyes and headed off to bet.

James met Sirius in the stands after placing his bet. "The guy looked at me like I was out of my head, placing that much money on Buttercup. I told him he was a distant relative and wanted to show my support. He told me that jockey don't actually know who bets for them."

Sirius laughed. "So much for your subtlety, Potter."

"Oh, shut it, Black."

The bleachers were filling up so Sirius and James decided to stand near the fence separating the spectators from the track. They needed to be as close as possible for Sirius to cast the spell effectively, and on the right horse.

"This would have been so much less complicated if we could just have converted more Galleons," Sirius complained as they waited for the race to start.

"Where's your sense of mischief, Pads?!"

"My sense of mischief is right up there, beneath my sense of efficiency. We don't even know if the spell will work! And what then? Where will get the money?"

"We'll get the money, Pads, don't worry."

Sirius sighed and shook his head. "Sorry, Prongs. I know I'm being a downer. It's just been very stressful at home. Moony's been moping…"

"He's not moping, Sirius. Jesus Christ. He's grieving!"

Sirius shrugged. "I just hate to get his hopes up if this isn't going to work."

Just then, a loud voice began to speak excitedly, rambling about horses and jockeys and the fine, fine weather folks. James and Sirius looked around, disoriented, for the source of the disembodied voice. Finally, they noticed the booth attached to the main building , on a higher floor, with windows lining the wall and a man wearing headphones talking into a large microphone; megaphones around the track blasted his words to everyone in the vicinity, whether they wanted to hear the man or not.

The nice thing about the Muggle world, James thought, was that everything had an explanation.

The man babbled on and on about statistics and allusions that Sirius and James neither understood nor cared to try and understand. They just wanted the race to get started.

Finally it did with the man in the booth scream "And they're off!"

James and Sirius stared, bored out of their minds, as the horses ran round and round the track. They really couldn't understand the strange phenomenon that caused the countless grown-ups behind them to jump to their feet and scream words of encouragement, or not, at the horses they had bid on. Finally, on the last lap, Sirius discreetly raised his hand, his wan trucked under his sleeve.

"Accelero." With the amount of noise made by the commentator and the spectators behind them, Sirius didn't even need to bother keeping his voice down.

Suddenly, Buttercup sprang forth and started passing by the other horses. The horse had her head down but its eyes were bugling like even she was surprised. The end line was nearing and she only had two more horses to pass.

Two more…

Buttercup was now head to head with the first-place winner. The jockey turned to look at Buttercup and urged his horses to go faster, but it was no use. Buttercup was under a spell and every step she took, her speed increased. She passed the finish line with the other horse's head at level with her behind.

Sirius quickly muttered the anti-spell and Buttercup came to an immediate stop; her jockey almost went flying off her saddle.

The crowd was going crazy, and the commentator was even crazier.

"Let's get out of here before these weirdos start a riot," James yelled to Sirius over the noise.

The guy behind the booth stared at James slack-jawed when he came to pick up his winnings.

"I've never seen anybody as you, kid. That horse looked possessed!"

James took the money and he and Sirius booked it out of the place.

A few days later, James had his feet propped up on the kitchen table and was reading the Muggle newspaper when Sirius walked in.

"Listen to this," James told him. "In the sports section, '5-year old racing horse Buttercup passed away two nights ago. The cause of death was reportedly a heartattack. It is believed that Buttercup's spectacular win on Monday afternoon was the cause.'"

Sirius gulped down a glass of water. "Shit. I told you we didn't know the consequences of the spell."

"At least she'll forever be immortalized by her spontaneous victory." James sighs, then added, as an afterthought. "How much of the winnings do we have left over? Maybe we should also get Buttercup a tombstone…"