This in not really meant to be 100% realistic.

Yes. This has gone through too many variations to count. It started as Max winning, then Piastri winning, then Max, then Leclerc. Right now, it is the current 2nd Version, ignore the versions where Max and Leclerc won :)

Here's a just for fun fantasy F1 2025 seasons I made. This does not completely account for all changes that are actually occurring in real life.
This was made after the Silverstone GP in 2024, and heavily updated after the Baku GP in 2024. Any changes that dont reflect what has happened since (Perez getting another season, Bottas staying at Sauber etc) will not be modified here.

OVERVIEW, DRIVER TRANSFERS, TEAMS AND CALENDAR
OVERVIEW
The 2025 Formula One World Championship was set to be a spectacle, with Max Verstappen looking to win his 5th straight championship and defend his legacy from the hungry McLaren, Ferrari and Mercedes duo's after a disappointing and unconvincing 2nd half of the season in 2024 saw him struggle to hold on. The unchanged McLaren pair of Lando Norris and Oscar Piastri would look to not only win a WDC, but to defend their teams WDD after a stellar 2024 campaign for the both of them, with Redbull, Ferrari and Mercedes all on their tails.
Whilst no constructors would make any changes to their entrants or engine suppliers, the moves in the driver lineups would be bountiful. Perhaps the biggest change would be Lewis Hamilton leaving the Mercedes team that he had won seven championships with to pair with Charles Leclerc at the Tifosi, leaving Carlos Sainz to salvage a seat at Willaims for the out of a job Logan Sergeant's mid season drop last year. Replacing Hamilton at Mercedes would be Kimi Antonelli, one of 4 rookies to join the grid in 2025 alongside Liam Lawson who had prior replaced Daniel Ricciardo at VCARB partway through 2024, Oliver Bearman who would find a seat a Haas following Magnussen's retirement and Jack Doohan at Alpine, who would replace Esteban Ocon after his move his move to Haas, whilst Zhou would depart from the grid and make room for Nico Hulkenberg at the team.
Apart from a little reshuffle, with Australia becoming the season opener and a few other small changes, the 2025 calendar would remain much untouched from 2024.

DRIVER TRANSFERS
Daniel Ricciardo:   RB Honda RBPT   ->   Retired
Liam Lawson:   No Seat   ->   RB Honda RBPT

Lewis Hamilton:   Mercedes   ->   Ferrari
Carlos Sainz:   Ferrari   ->   Williams
Kimi Antonelli:   No Seat   ->   Mercedes
Logan Sargeant:   Williams Mercedes   ->   No Seat

Kevin Magnussen:   Haas Ferrari   ->   Retired
Esteban Ocon:   Alpine Renault   ->   Haas Ferrari
Jack Doohan:   No Seat    ->   Alpine Renault

Nico Hulkenberg:   Haas Ferrari   ->   Kick Sauber Ferrari
Oliver Bearman:   No Seat   ->   Haas Ferrari
Zhou Guanyu:   Kick Sauber  Ferrari   ->   No Seat

TEAMS AND DRIVERS

SUMMARY
Races 1-6:
Oscar Piastri would finish the first 25% of the season in the championships lead, with 2 early wins and a handful of podiums placing him on 114 points. Max Verstappen wouldn't be down on his hopes for a 5th consecutive championship yet, propelling himself from 4th to 2nd in the standings in a handful of races with back to back wins in Saudi and Miami. Despite failing to win a race yet, Lando would find himself a little behind the 2 at the top in 3rd, whilst Alonso would find himself in 4th after Adrian Newey's AMR25 would help him finally win race number 33 in China. Hamilton would also pick up his first win in Red, whilst further down the pack Carlos Sainz would pick up 11 points in a struggling Williams and Liam Lawson would manage 8 points after a 6th place finish in Japan, placing him ahead of his yet to score teammate and a disappointing starting Kimi Antonelli.

Races 7-12:
Come the seasons halfway point and Oscar would find himself further in the championships lead after 5 consecutive top 3 finishes, whilst Max would just barely hold onto 2nd ahead of Lando after his win at Silverstone. Back to back wins in Spain and Canada saw Russell find himself up to 4th in the standings, with Charles Leclerc not to far behind after a win in Imola. Further down the field and Alonso would find himself sliding down the order in an Aston Martin that just didnt have the pace it did at the seasons beginning, whilst Kimi Antonelli would find himself consistently scoring points now, scoring 24 points in the last 6 races as opposed to just 7 in the first 6. Sainz and Gasly would continue picking up points in their awful cars and Haas would remain without a point.

Races 13-18
A win in Singapore would see Piastri  maintain the WDC lead going into the final stretch of the 2025 season, however it would no longer be Max or Lando behind, as a stellar part of the season from Leclerc would see him win 3/6 races and boost himself up into 2nd in the standings. Max would be a stark contrast to the Monacan, falling from 2nd to 4th and potentially even looking at ending as low as 5th. With his teammate looking just as disappointing, Red Bull would slide to 3rd in the standings and depending on how Mercedes perform could end up as low as 4th. The rest of the grid would be pretty uneventful, and the F1 world would look to the final 6 races and 3 sprints to see who would be the World Champion.

Races 19-24:
"Oscar Piastri, you are the Champion of the world"
That was Tom Stallard's words over the radio upon the final lap of Qatar.
6 race wins, 15 podiums and 416 points, that is what it took. Crossing the line in the place the young Australian took his very first sprint win as not only a Qatar Race Winner, but much more importantly the Champion of the World. A talent for generations and generations to come, Oscar would come the first McLaren World Drivers champion since young Lewis got his first in 2008.