One idea could be that Gohan and Towa are forced to team up against a common enemy from another dimension. They start off distrusting each other but as they face challenges together, they begin to understand and respect one another's powers and motives.
One plot idea could be that Towa, who is a villain - ish character, has a change of heart and teams up with Gohan to protect the Dragon Ball universe from a new, powerful threat. Maybe they have to travel to different dimensions to gather special artifacts to defeat this threat, and along the way, they learn to understand and respect each other's powers and motives.
One idea could be that Towa uses her time - related powers to create an alternate timeline where she and Goku have to team up against a new, powerful enemy that threatens both their worlds. This would force them to work together and understand each other's powers better.
Maybe in the fanfiction, Android 18 gets injured while protecting Gohan from a new powerful enemy. Gohan then takes care of her and in that time of vulnerability, they realize their feelings for each other. This could lead to them exploring a relationship while also trying to figure out how to defeat the enemy that still lurks.
A really interesting plot could be that Vegeta discovers Gohan has a hidden power that even Gohan himself is not fully aware of. Vegeta then decides to help Gohan unlock this power. Along the way, they face many difficulties and their relationship changes from just acquaintances to true friends. They might also encounter other characters from the Dragon Ball universe who either help or hinder their journey.
One idea could be that Frieza, after being resurrected yet again, finds himself in a situation where he has to team up with Gohan. During their time together, they start to understand each other's motives and past traumas. Gohan's kindness and sense of justice gradually influence Frieza in unexpected ways.
One idea could be a time - travel plot where Towa ends up in the Naruto universe. She could have some unique abilities that catch the attention of Naruto and his friends. They might initially be suspicious but then come to realize she can be an ally in fighting a new, powerful enemy.
Well, the OC could be a descendant of an ancient race that has a special connection to the energy that Towa uses. Towa wants to use this connection for her own gain. As the story progresses, the OC discovers their heritage and uses it to fight back against Towa. Or, the OC might be a lost soul who Towa finds and tries to corrupt. However, the OC's pure heart resists her influence. Additionally, the OC could be a new recruit in the Time Patrol who is assigned to deal with Towa. During their encounters, an unexpected bond forms between them.
One idea could be that the female Saiyan is from a different part of the universe and she and Gohan meet during a galactic tournament. They start as rivals but gradually develop feelings as they see each other's strength and honor.
One plot idea could be that Videl discovers Gohan's Oozaru form in a secret forest area. She's initially scared but then realizes it's still Gohan inside. As she tries to help him regain control, they form a deeper bond.
One idea could be that Naruto and Fem Gohan meet in a dimension - hopping accident. Naruto is intrigued by Gohan's Saiyan strength and her different fighting style compared to what he's used to in the ninja world. Gohan, on the other hand, is interested in Naruto's never - give - up attitude and his unique jutsu.