[Damn it, I can’t get this idea neither out of my head nor into coherent words, so I’m going to take advantage that no one cares about this blog to ramble here]
Senju and Uchiha are hero families, with an aggressive rivalry for the #1 spot since a few generation before (quirks are relatively new as in Bnha)
Uchihas are strictly fire users, and despite they are really invested in the rivalry, they are quite reasonable about it. Tajima married a civilian with no strong quirk for love, and of his five kids he let three of them chose other careers/retire pretty easily.
Senjus are still renowed as a family of a thousand skills, but the main family are almost all wood/mokuton users, famous for their incredible resistance, given their quirk doesn’t have any other drawback than tiredness, and even then they make up for it with thier legendary stamina
Madara and Hashirama have already graduated. They were classmates at the Konoha Academy (K.A.), and of the idea of ending their families rivalry by opening together an agency, but because of Butsuma’s influence on Hashirama (forcing him to do all his internships under him) and Madara jealousy of his friend’s relationship with Mito (he took the rejection of his unspoken crush badly), they had a fallout during their second year.
Madara’s bitterness worsened in the years since not only Hashirama always beat him during school, but in the three years since they debuted the eldest Senju brother is already #1 thanks to an incident in which he saved the day and gained endless popularity. Meanwhile Madara is ‘only’ #6 despite his strenght, on account of his abrasive personality
Mito’s quirk is Adamantine Chains, she is #9; Touka has her illusions, she is #15
Tobirama and Kawarama are fraternal twins and in the same year as Izuna, but all three are in different classes. They are 3 years younger then their older brothers
Despite Madara staking a lot of pressure on Izuna to win the sport tournament he flunked it terribly during his 1st year because he underestimated Tobirama. Having won easily against Kawarama’s mokuton, he hadn’t deemed worth gaining intelligence on the other twin, not considering that not only Tobirama ranked first in the entrance exam, but that his mother is the water user hero Moon Tide
Tobirama would’ve chosen the Support course, but his father forced him to enroll to the Hero one, to the point they are still not talking to each other. The only reason he decided to fight Izuna seriously was to vindicate his twin’s humiliating defeat
Their 2nd year the sport festival was cancelled because of the incident Hashirama later gained his #1 spot for
The story starts at their 3rd year sport festival, where, despite Izuna this time taking all the matches seriously and winning uncontested, both the Uchiha brothers are dissatisfied, as Tobirama didn’t use the whole range of his quirk
Madara confronts him later, commenting about how his poor showing today won’t help his initial place in the rankings after he graduates, to which Tobirama comments he is there to get the work done, aka helping people, and not to win some ‘popularity contest’
Moved by that conversation, Madara remembers the core reason he had wanted, years ago, to open an agency together with Hashirama. So, the next time, instead of trying to steal the win from his old friend he collaborates with him against the villain and lately accepts Hashirama’s proposal (he had started to suggest it again in the previous year, as soon as his position as #1 freed him enough from his father’s influence)
The story jumps to 2 years later, to Madara finding Tobirama in the crowd of the sport festival at K.A., there to see Itama competing. He comments how the younger man had made a name for himself as a support tech [his techs share the same names as his canon jutsus], and implies he suspect he is also the underground hero the underbelly of the city is talking about. He then proposes him to stop suffering the tribulation of working on his own by joining their agency.
Tobirama comments how their agency isn’t going so well in rankings, Hashirama has dropped a few rankings, now being #5, while Madara is #8. Madara comments he doesn’t care anymore for it, the area under their protection has never been safer, and that’s the only thing that matters.
Clealry satisfied by that answer Tobirama suggests he may be interested, to which Madara replies they could talk details in front of a coffee, the other accepts [heavy implication of it being also a date]
Hashirama and Madara have lost rankings because disengaging from the family drama made them lose popularity: people are too invested in the pettiness of the rivalry to reward any hint of losing it. Also the difference of going from Senju/Uchiha resources to starting from zero was noticed by the public
Izuna still decided to join the Uchiha agency, and views Madara’s choice as a betrayal (but nothing as drastic as in canon, a few cutting remarks at family dinners at most)
Kawarama joined the Senju agency, more to continue its legacy than for loyalty to his father. Later, when Butsuma retires, he will have no qualms on collaborating openly with his eldest brother’s agency.
Itama has both his parents’ quirk, split in the middle like his hair, but the water quirk drawback of freezing from overuse means his other side is affected at the same time, making him actually weaker than his brothers. He will join Hashirama’s agency for a while as a hero, but realising he isn’t anymore under his father thumb, he will chose to retire early for a desk job within it
