Cell Arc - Part 4
Within the days leading up to the Cell games, Gero has started to gain mixed feelings about his creation. Having not gained Freeza's cells in this timeline, Cell has far less natural evil, with the overabundance of Saiyan DNA making his desire to fight and test his limits far more sincere and less focused on his privilege of "muh Perfection", though it still exists to some extent due to Vegeta's cells. On one hand, Gero enjoys the irony that he'll get to see Goku die once again, this time by the hands of a being so similar to himself, but on the other, he sees Cell as someone he can't control in any way close to his previous works. Pondering on this, Gero heads back to his lab, which he'd have made #17 and #18 keep intact when they activated.
The day of the Cell Games arrives, with all the fighters arriving. After their Rosat trips, all the Super Saiyans have Ki at bare minimum above what SSJ Gohan had at this point, Piccolo not being too far behind either at around Goku's strength in the main timeline, making Cell both excited and slightly scared at the prospect of being faced with 7 warriors of such a level. Gero would've also returned at this point, but would hide back in fear at how strong everyone had become. Mr. Satan arrives and of course easily defeats Shello....in his dreams. The Saiyans would then debate on who should face Cell first, to which Raditz says Trunks should, telling them from their training, he's seen Trunks surpass the level of a Super Saiyan with his natural talent. However, Goku says the same about Bra, also noting that with her having travelled to save this timeline and Cell having killed an alternate timeline version of herself to get here, it's only natural for Bra to defend the timeline. Overall, Bra is chosen to go first. Bra would also likely be carrying a pack of capsules, which she hands to Goku before facing Cell, though Piccolo then requests to hold onto them "just in case".
Cell then powers up to his full speed and starts to fight fairly well with Bra's Super Saiyan form, though needs to power up more than against Gohan to keep on even footing. The fight takes many turns, with Cell's array of techniques keeping Bra on her toes much in the same way they did her father in the anime. After a drawn out exchange, Cell reveals that he still isn't using all of his power, to which Bra replies neither is she, going into Super Saiyan 2. Everyone is shocked, especially Cell and Gero, apart from Goku who looks on in admiration at his daughter's power. Trunks also exclaims that Bra has the same form as him, surprising everyone other than Raditz. Goku then thinks about how proud he is that both his children have gotten so strong.
Cell would then be at a loss for words, knowing how outclassed he was. He'd then focus on keeping his distance with attacks such as the Kienzan and his Perfect Barrier, as well as use a Taiyoken to score some good hits on her, though much like his canon self, it'd take just two punches for him to spit out #18 and make things more hopeless. Whilst he'd be angry that his Perfection was surpassed and lost, he'd be able to accept his fate and be glad he got to face such a strong opponent. Before Cell can meet his end, however, Gero than presses a switch, causing Cell to expand. Gero had spent several days creating a button to activate Cell's self-destruct mechanism just in case things went awry, having sensed Raditz and Trunks' power from the first Rosat trip. Whilst everyone was distracted, Gero would attempt to flee using a Spaceship capsule, though would be stopped by Trunks. Due to Gero's actions being the main catalyst of Goku's death, Trunks would've kept most of his attention on Gero and gone Super Saiyan 2 as soon as Gero attempted to flee to cut him off. Trunks would then destroy Gero's body with a single strike, leaving only the head.
Meanwhile, Piccolo would note that it's lucky Bra brought some capsules. He'd shout at Bra which Capsule has some kind of container in and activate it, then materialising a talisman on it and performing the Mafuba on Cell, the Mafuba would be a success and trap Cell inside, making everything seem at peace, though Piccolo would've used up all his Ki for this. In this moment, Piccolo would suddenly be shot with an energy beam and from his fatigue, would die from it. The source of this was Gero's head, using what reserves of energy it had left. Whilst everyone was focused on Piccolo, it would've shot a smaller eye beam at the container, releasing Cell. I don't believe his self destruct would've been paused, as being sealed didn't stop Daimao's aging, so when Cell emerges, it's in his Super Perfect form.
Cell's first action is heading towards Gero's head, saying he's thankful that the Doctor allowed him to gain so much power, but is gratitude is just as great as his anger at having been used like that. Before Gero can respond, Cell crushes his head beneath his foot, before turning to everyone else. He then notes he has no concern about world domination or destruction, only victory in battle and proof of his Perfection. Hearing this, Bra's anger subsides and she agrees to fight Cell not as an enemy, but as a rival, though due to Saiyan Arc Vegeta, Raditz and Piccolo's cells, Cell tells her that doesn't mean this won't be a fight to the death.
The two continue fighting, with Bra's power advantage being evident, though Cell's superior skills are able to close the gap slightly. There's a limit to how much he can take, however, with regeneration draining his stamina when not severe enough to gain another Zenkai, leading to Bra eventually being able to land a deciding blow. Cell, being beaten to the ground, would then say that Bra has earned this kill to avenge her other self and save the future. However, Bra decides to spare Cell, saying that her experiences in this timeline show that Gero was the source of his creation's evil and that Cell is almost made entirely of those who are now her allies and that she can see he too can change. Whilst Cell is honoured by this, he still says it would be improper to stay there after killing so many humans and decides to leave the Earth, using Cold's cells to venture into space as part of his own training. Before departing, he tells everyone that he'll reach a level that can truly be called Perfect and that they should make the Cell Games a regular event. They then part ways, with feelings between the Saiyans being mixed between letting a powerful foe escape, the possibility of his redemption and the excitement of having such a strong rival. For the same reason, I imagine they wouldn't kill their timeline's Cell, of whom they likely wouldn't have had the time to destroy yet.
Several months later, Yamcha and the rest return with Dende and Shenron revives all those killed by Cell and removes #17 and #18's bombs. Bulma also gives her future daughter a map of coordinates to New Namek so that she can restore Earth's Dragon Balls in her timeline. As Bra and her child return to the future, Vegeta decides to go with them, with there being nothing worth staying here for and having found a rival (and more) stronger than Kakarotto or Raditz. They then depart, with Vegeta telling them he'll still visit as often as he can to prove his dominance to the lower class Saiyans and everyone returns to their peaceful lives.