Daisuke and Boruto's Originsnaruto and sasuke always had a strange relationship. they were in love, but due to social pressures and interpersonal struggles between them they never were an official couple. their typical routine would follow as such: one of them would suddenly meet up with the other. they'd fall back in love; kissing, cuddling, and doing regrettable things, usually causing naruto to fall off the radar during that period. one of them (usually sasuke) would succumb to the 'what-if's and cause the relationship to end, sending sasuke back out on his one-man journey and naruto to go back to life in konoha.
well. one of these times, somehow, (either because naruto is trans or due to the sexy jutsu,) naruto accidentally got pregnant. there was no 9 months. the spirit of the nine-tailed fox caused his pregnancy to last about 2 months, during which he had to hide away to avoid being found out. daisuke uchiha was born, and quickly naruto went back to his typical life and tried to forget about the whole ordeal. sasuke took daisuke away with him to raise him on his own.
5 years later, after having no contact with sasuke, naruto had a son with an unknown person. again, it was an accident. naruto knew that he couldn't disappear again, so he owned up to the fact that he was having a son. 2 months later and boruto uzumaki was born.
7 years after that (daisuke learned abt naruto during this timeframe), sasuke and naruto fall back in love, causing sasuke and daisuke to come to konoha. they stay at the hokage building, separate from naruto and boruto's home. they still kept things under wraps, even from boruto and daisuke. however, daisuke knew.
naruto and daisuke ended up with an odd relationship; daisuke knew that naruto was his father, but naruto thought that daisuke was oblivious. they end up like a weird step dad and step son. daisuke still holds some resentment towards naruto because, in daisuke's eyes, naruto rejected him, causing him to have a rough childhood.
daisuke feels some envy and bitterness towards boruto, but still really likes the kid. boruto doesn't know daisuke is his brother.