I'm not sure about a specific 'Ichigo and Orihime lemon fanfiction' title off - hand. But you can often find great ones on fanfiction websites. Just search for 'Ichigo Orihime relationship fanfiction' and look through the results. You might have to sift through a bit to find the ones that are well - written and suit your taste.
Ichigo could start to take more interest in Orihime's hobbies and vice versa. This would show that they are not just a couple who love each other, but also friends who want to know each other better. For instance, if Orihime likes cooking, Ichigo could start to learn cooking from her and they could have some lovely family dinners together.
There's a fanfic called 'The Bond of Hearts'. It's set in an alternate universe where Ichigo and Orihime are childhood friends. It shows their relationship evolving over the years. It delves deep into their emotions and how they gradually realize their love for each other. The character development in this fanfic is quite engaging.
Their relationship would likely become more intimate in a different way. There would be a deeper level of trust and reliance. Ichigo would see Orihime in a new light, as the mother of his child.
Many fanfics focus on the development of their love. Some might start from the early days when they were just friends in the story. They gradually realize their feelings for each other through various adventures and challenges, which makes the love story more engaging and full of twists.
A fanfiction could focus on Ichigo attending the school in Highschool DxD. His presence would surely disrupt the normal balance. He might not be interested in the whole 'devil' and 'angel' thing at first, but gradually get involved. He could also introduce some of his Soul Reaper training methods to the students there, which would be very different from what they're used to.
First, you need to understand the characters well. For Ichigo, know his personality traits like his determination and his sense of justice. For the Highschool DxD characters, understand their hierarchies and their goals. Then, come up with a unique plot. It could be a battle - oriented story where Ichigo and the DxD characters fight a powerful enemy together. Or it could be a more slice - of - life story where Ichigo adapts to the strange new world of DxD.
It could be a rogue Soul Reaper. Maybe someone who has turned against the Soul Society and sees Ichigo as a threat or a valuable asset. They might want to use his power to gain control over the Hollows or to overthrow the existing power structure in the Soul Society.
There could be a love story where Ichigo has a time - travel adventure and meets a version of Orihime from the past. This Orihime is different in some ways, yet still has the same kind heart. Ichigo has to keep his identity a secret at first, but as they interact more, he can't help but be drawn to her. She also feels a strange connection to this mysterious boy. As Ichigo tries to find his way back to his own time, he realizes that he has fallen in love with this different - yet - the - same Orihime, and the story becomes a race against time and his own heart.