Once upon a time, there was a fancast where they imagined all the characters from a fantasy world as modern-day office workers. The powerful wizard was the CEO, who would always accidentally turn his coffee into a magic potion. His secretary was the fairy, constantly using her wings to flutter around and deliver messages in a very disorganized way. It was a really hilarious concept that made everyone laugh.
A group did a fancast where they made all the villains from different movies live together in an apartment. The Joker from Batman was constantly playing pranks on Darth Vader, like putting whoopee cushions on his chair. Sauron from Lord of the Rings was always complaining about the lack of a proper 'evil lair' in the apartment. It was a chaotic and humorous situation as they all tried to out - evil each other in a very domestic setting.
You could have a bittersweet ending where the couple realizes they can't be together but still have love for each other. That leaves the readers with a mix of emotions.
Another challenge is in his relationships. He may worry that people pity him or treat him differently because of his blindness. For example, in some fanfics, he has to prove to Lily that he's still the same James she knew before, just with a new disability to deal with. Also, in duels or battles, not being able to see his opponents' movements directly puts him at a disadvantage, so he has to develop new strategies to defend himself.
He could meet the descendants of his friends, like the grandchildren of Ron and Hermione. They might show him around the future wizarding world and tell him about all the changes that have occurred. Also, he may run into some new and powerful wizards who have emerged in the future and learn from them about new magical techniques.
I think actors like Emma Watson and Tom Holland could make a great pair for a novel love story. Their chemistry and acting skills might bring the story to life.
Perhaps James had some hidden magical ability that he was unaware of until that moment. It could be something that was passed down through his family but had never manifested before. This ability could have protected him from Voldemort's killing curse. Or, it's possible that there was a plot by some other characters to save James. There could have been a group of wizards or witches who had been secretly working to keep James alive because they knew his importance in the fight against Voldemort. They might have used some sort of time - turning magic or a protective charm that Voldemort couldn't break through.
One great 'Harry Potter James Potter' fanfiction is 'The Marauders' Era'. It delves deep into the friendship of James Potter and his friends. It shows their adventures at Hogwarts, like their pranks on Snape. The characters are well - developed and it stays true to the original Potterverse feel.
His father, Harry Potter, might also send a Howler. Harry knows the importance of discipline and responsibility, and if James was shirking his duties or not following the rules at Hogwarts, Harry would not hesitate to use a Howler to communicate his disappointment and expectations.
Well, it could make James more protective of his remaining family and friends. He might become more serious and less carefree, as the loss of a sister is a huge blow. It could also fuel his determination to fight against whatever forces caused her death, like in the wizarding world, it might be dark wizards or some sort of magical curse.