She could be from a hidden clan. Maybe her clan was in charge of protecting a powerful and ancient artifact. But when the Nighloks started getting more aggressive, her clan decided it was time for her to join the Power Rangers. Her skills with the katana, which she learned from her clan's strict training regime, would be a great asset to the team.
The Pink Ranger could be an interesting character to pair with the Black Ranger. Maybe they have a love - interest kind of relationship where their different personalities clash at first but then they grow to understand and care for each other. Also, a villain who has a personal vendetta against the Black Ranger could be paired with him in a story. This would create a lot of tension and conflict, making for an exciting plot.
A great plot might involve the Black Ranger getting lost in a different dimension while on a mission. In this dimension, he has to adapt to new rules and powers while trying to find his way back. He could meet new allies or face enemies that are unique to that place. Also, a plot about the Black Ranger having to train a new recruit who has a lot of potential but also a lot of recklessness could be interesting.
Her powers could be more focused on stealth. While the other rangers are great at direct combat, she can move silently and strike without being noticed. For example, she might be able to turn invisible for short periods, which would give her an edge in surprise attacks.
One plot idea could be the female red ranger having to prove herself in a male - dominated ranger team. She could face discrimination at first but then show her unique skills in combat and leadership, winning over her teammates. Another idea is that she discovers a new power source that is related to her femininity, like a power that is linked to the power of nature and female intuition. Maybe she has to go on a solo quest to master this power while the rest of the team is dealing with a different threat.
One possible love story could be that Jayden meets a new ranger from another team during a joint mission. They start off as comrades but gradually realize their feelings for each other as they face various challenges together. Their love blossoms as they support one another through tough battles against powerful enemies.
Another idea is a character swap. Picture Naruto as a Power Ranger Samurai. He would bring his ninja skills and determination to the team. His Rasengan could be transformed into a special attack for his Samurai Zord. Or, a Power Ranger Samurai could be sent to the Naruto world and have to learn ninja techniques to survive and help the village.
One great 'Power Rangers Samurai' fanfic is 'The New Samurai'. It has an interesting plot where a new ranger with unique powers joins the team. The character development in it is really well - done.
I'm not sure specifically about 'Power Rangers Samurai' gay fanfics. Fanfics can vary greatly in quality. You could try searching on popular fanfic websites like Archive of Our Own. They have a wide range of fan - created works, and you might be able to find some that fit your interest.
A powerful witch - like villain would be great. She could be jealous of the female red ranger's power and beauty. This witch could use dark magic to create illusions and traps for the ranger. For example, she might make the ranger think her teammates are in danger, causing her to make hasty decisions. Another option is an alien warlord who wants to conquer Earth and sees the female red ranger as a major threat to his plans. He could have advanced technology that the ranger has to outsmart.