One plot idea could be that Demon Yusuke has to protect Keiko from other demons who see her as a way to get to Yusuke. Another could be Yusuke trying to balance his demon side with his relationship with Keiko, like when he has to hide his new powers and instincts from her at first. Maybe there could also be a plot where Keiko discovers a way to temporarily become a demon herself to be closer to Yusuke's world.
Well, a plot could involve Keiko being kidnapped by a powerful demon who wants to use her as bait to draw Yusuke into a trap. Yusuke then has to gather allies from both the human and demon worlds to rescue her. During this time, Keiko discovers some hidden powers within herself that she never knew she had. This could change the dynamic of their relationship as Yusuke now has to deal with a stronger and more self - aware Keiko, and they both have to figure out how to incorporate these new changes into their relationship.
One idea could be that Demon Yusuke has to protect Keiko from other malevolent demons while hiding his true nature from her at first. As the story progresses, Keiko discovers his secret and has to come to terms with it. Another plot could be a time - travel scenario where Yusuke goes back in time to save Keiko from a danger that she faced in the past, which changes the course of their relationship in the present.
One possible plot could be that Keiko is caught in the crossfire of a demon battle that Yusuke is involved in. Yusuke, being a spirit detective, has many enemies. Maybe a powerful demon targets Keiko to get back at Yusuke. After her death, Yusuke could go into a deep state of despair and vow revenge. He might journey to the spirit world to find a way to bring her back, facing numerous challenges along the way.
There could also be a fanfiction where Yusuke and Keiko get trapped in a parallel universe. In this universe, things are slightly different but their feelings for each other remain the same. They have to adapt to the new environment while also trying to find a way back home. Their love and determination keep them going through all the difficulties they encounter in this strange new world.
Yusuke would likely become more withdrawn. He was always a bit of a rough - around - the - edges character, but Keiko's death would make him more somber. He might lose his sense of humor that he sometimes showed around her.
One idea could be that they struggle at first with the news of Keiko being pregnant. Yusuke, being his impulsive self, might initially panic but then quickly step up to support Keiko. He could start taking odd jobs to save money for the baby. Keiko, on the other hand, would be the calm and organized one, preparing for the baby's arrival by reading all the parenting books she can find.
The relationship can be developed through shared experiences. For example, if they face a common enemy together. Yusuke's demon powers can be used to protect Keiko, which deepens their bond. Also, communication is key. Yusuke can open up to Keiko about his new life as a demon, and she can share her fears and concerns about his transformation.
Growth is another theme. Yusuke often goes through a lot of changes, and Keiko is there. Fanfictions might show how they both grow as individuals and as a couple in relation to those changes. For example, Yusuke becoming more responsible and Keiko being more understanding.
The relationship could develop in a rather unique way. Maybe Yusuke saves Keiko from a life - threatening situation, which makes Keiko see him in a new light. Yusuke, on the other hand, is drawn to Keiko's purity and kindness. As they spend more time together, Yusuke starts to change for the better because of Keiko's influence. Their relationship might be full of misunderstandings at first, but as they communicate more, they grow closer and closer, eventually falling in love.
There's this fanfic called 'Together Always' which is really interesting. It delves into how Yusuke and Keiko handle the challenges in their relationship. It shows Yusuke's growth as a character in the context of his love for Keiko. Keiko, on the other hand, is depicted as being very supportive of Yusuke's journey.
Yusuke might cope by throwing himself into his work as a spirit detective. He could try to distract himself from the pain of losing Keiko by taking on more and more dangerous cases. This would be his way of running away from his emotions at first.