What if instead of Cedric Diggory, Marcus Flint had participated in the Triwizard Tournament in Harry Potter and the Goblet of Fire
To the events of Harry Portter an the Goblet of Fire make sense, i simply change their age subtracting one year to Marcus, Oliver, Percy and litteral all the Slytherin Team.
Marcus don't really want to participated in the tournament his name was put in the goblet for a bad joke of Pucey and Montague.
Maybe Albus Potter and Scorpius Malfoy had something too see with Marcus's name came out of the goblet and not Cedric's
He litterally just accept because Viktor Krum is one of the competitors and because he has no other option.
In a way Oliver was angry because he also put his name to into the goblet and was not chosen, but that didn't last long.
FlintWood? OF CURSE.
Marcus and Oliver at this time had a fight that almost ended in their breakup
On Oliver's request, Percy helped Marcus in an unknown way in the trials
I literally have a lot of sketch of this shit in my notebook.
-First Task-
Oliver: Are you CRAZY!, you could have died, why you always have to be so immature about you life Flint!
Marcus: But i won, no?
In the first task, Oliver asked Percy to help Marcus to literally not die in the test but Marcus did not care about Percy's advice, in the end he manages to pass the test getting the golden egg but with more difficulty of the pensively initiated.
At Marcus's immaturity, Oliver gets angry entering a fight with Marcus about his silly plan, which Marcus believes is an exaggeration on the subject since it had worked out well, after that fight they did not speak or approach again.
Actually, after Harry Potter, who was the last participant, passed the task, Marcus felt really dumb for not thinking about using his broom like him, because he may not be as fast as Harry, who is a seeker, but yes the necessary to dodge a dragon.
More than congratulating Marcus to pass the task the people of his house just say him to not messed up and not be a deception of Slytherin house, commentaries that obviously doesn't matter to Marcus.
-Second Task-
Marcus: Why do you still help me Wasley?
Percy: Just take it as a favor Flint, i don't think i can stand Oliver if something happens to you.
Even though Oliver stopped talking to Marcus, Percy still helped him with the second task.
Thanks for the twins who heard him from Mad-Eye Moody "Barty Crouch" Percy knew what to do with the golden egg, leaving free permission for the prefects bath
Marcus doesn't really hate Harry, so in his own way he tells her about the track for the second task, Harry at first doesn't believe Marcus just because he is him, but for lack of ideas he does what Flint told him.
For the task he use the Bubble-Head Charm that in fact it was his idea.
Marcus never imagine to find Oliver in the task he actually thought that what they had taken was something material.
Seeing that the person that Harry was going to take was Draco, Marcus knew that he had won a big bet with his team.
If Marcus believed everyone in the school was dumb and blind to see the obviosly things, he believed it even more when people thought Oliver had been taken to the task because of the rivalry they both had.
After the task Oliver and Marcus stopped fighting.
-Third task-
Marcus: Look Potter I don't usually care what people think of me, but believe me I can be everything you want except a traitor.
Harry: I know...
In this point Marcus just ant to finish the tourment so he didn't ask to Percy and Oliver for help, Oliver don't say anything with that decision.
In the maze Marcus protected Harry from Viktor Krum who was left behind the Imperius Curse.
Actually he tried to help Fleur when he hearded scream, but he never found her.
After help him in the past task Harry thinks a little better about Marcus like a person, that why Harry decide to help him in a part of the maze
The two did not fight over who was going to take the cup first (like Cedric) because they literally touched it at the same time.
When Harry and Marcus touch the cup, teleports them to the cemetery, Marcus has a bad feeling about the situation and more when Harry says they need to go back to where the cup is.
The parents of Marcus more than anything his father are Death eaters, thats the reason why he dont be attack for wormtail when he apear with dark lord.
When Voldermore returns and Marcus's father appears with the others death eaters, he congratulates Marcus in front of everyone because he believes that Marcus has something to do with his return, when the truth is that Marcus knows nothing about what is happening.
For fear he didn't fight back or tried to help Harry for the beginning.
That is the moment when Marcus gets the dark mark and at that moment the only thing that happened in Marcus's head was that Oliver was going to be disappointed in him.
Harry yells at Marcus some things about what a traitor is like and other things that make Marcus angry, but he can't defend himself in that situation.
Marcus without those present noticing and with the help of his father who really did not want him to get involved in that for his mother, helps Harry out of the fight to make it easier for him to approach the cup, obviously after the spirits of Harry's parents appear to help him too and those things.
When they returned, Harry told everything about what happened in that place without the parts of Marcus being a "traitor" (like the movie but without a death) and after all that Marcus forced Harry to talk to him about what happened.
-Some extra stuffs-
As they were fighting at the time, Marcus took Daphne Greengrass to the dance obviously in exchange for some things she asked for.
Maybe jealous Oliver cast a spell on Daphne to enchanted her shoes.
After Oliver and Marcus stopped fighting they both had their little dance that they didn't have for the fight
Marcus told him everything about what happened to Oliver, Oliver did not speak or criticize him, he only said that he did not want him to become his father something that Marcus promised him not to happen.
Currently, there is a photo in the Flintwood house and it is the only one Marcus has (not including those at the wedding) with Harry in the tournament.
