You can start by checking out your local bookstore. Go to the sections for urban fantasy and romance, and look for titles that seem to combine both elements. Often, the covers or blurbs will give you an indication.
Another great one is 'The Fever Series' by Karen Marie Moning. It has a unique blend of urban fantasy with a strong romantic sub - plot. The story is set in Dublin and involves a lot of mystery, ancient magic, and a passionate relationship between the main characters.
One possible fanfiction could be about Vegeta's attempts to balance his training with family life. He might struggle to find time for Bulma and their family while also trying to keep up with the threats in the Dragon Ball Super universe. For example, he could be training for a new powerful enemy, but Bulma wants him to be more present at home. So he has to find a way to make both work.
One great fanfiction idea could be that Vegeta takes Bulma on a special training trip. He wants to show her the different planets he has trained on. This would be a unique adventure for them both, allowing Bulma to see the vastness of the universe Vegeta has experienced. It would also strengthen their relationship as they face various challenges together during the journey.
The plot could be about Bulma getting kidnapped by a new villain. Vegeta goes on a rampage to find her. He battles through hordes of minions until he finally reaches the villain's lair. There, he has an epic battle and rescues Bulma. Afterward, he realizes how much he truly loves her and vows to protect her better.
It could be a genetic mutation in the fanfic's storyline. Some strange event or factor could have caused a change in Bardock's genes, making it possible for him to become Super Saiyan. This genetic change might be related to some ancient Saiyan lore or a new element introduced in the fanfic's universe.