Wolverine is one of the core characters of the X-Men franchise that has seen a lot of his backstory explained through the X-Men films. Although Logan introduced the character of X-23, who is a clone of Wolverine, the films never explored any of Wolverine's other children. Logan's kids span across the various Marvel universes, including the main universe and the alternate MC2, Ultimate, Mutant X, Earth-9811, Earth-13729, and Earth-295 universes, but none on them have been seen on the big screen except X-23.
One of Wolverine's most well-known children from the main Marvel Universe that has never had his story shown in cinemas is the character Daken. Daken, also known as Akihiro, is Logan's child with his now-deceased wife Itsu from his time in Japan. Just like his father, Daken has retractable claws and regenerative healing power. However, his powers aren't an exact copy of Logan's. The healing factor that Daken uses is not just automatic like Wolverine; it is affected by his mental state. Daken's healing factor can be slowed by psychological blocks such as guilt. His claws differ too, as they're black in color with one claw coming out from his wrist instead of knuckles. Daken also has extra powers that Logan doesn't possess, including pheromone manipulation and control.
Daken has had a troubled past that would have been perfect for an origin story, that goes all the way back to his birth. Itsu was murdered by the Winter Solider in his mission to return Wolverine to Madripoor. Daken was then cut out from his dead mother's womb by Romulus, but due to his healing powers, Daken managed to survive. Daken was then left on the doorstep of his Japanese adoptive parents, but his life did not have a fairy tale ending. Instead, it was full of bullying and the deaths of loved ones.
There are so many stories within the X-Men franchise that Daken has been a part of. He first appeared in Wolverine: Origins, where he infiltrates S.H.I.E.L.D and confronts his father. He temporarily kills him by slashing his stomach and leaving him to bleed, just like how Itsu did. Daken was part of the Dark Avengers team that debuted as part of the Dark Reign comic event. The team, created by Norman Osborn, is one of the most villainous comic book teams of all time. He was also known as Dark Wolverine in the Utopia comic as part of Emma Frost's Dark X-Men and in the solo Dark Wolverine run. Daken and X-23 have teamed up a few times in the comics, so introducing him as a character after X-23 appeared in Logan would make perfect sense. He has been part of the Brotherhood of Mutants and was also been involved in storylines with Apocalypse after becoming one of the Horseman of Death.
One possible reason that Daken's story-line has not been explored is that he could potentially be being saved to have a bigger part in one of the Marvel Cinematic Universe films now that Disney owns the X-Men franchise. With superhero films often being criticized for not having enough LGBT representation, Daken's bisexuality would also open up another avenue for the films to explore.
The main Avengers team came to an end in Avengers: Endgame, with new characters such as Captain Marvel setting up the next phase of the Marvel Cinematic Universe, but a Dark Avengers film is a potential team-up that is yet to be explored. There were rumors that a script for a Dark Avengers film was in development back in 2018, but since then the involvement of the Dark Avengers in the next phase has only been speculation. Regardless, it would be a welcome sight to see Daken on the big (or small) screen.