Well, a plotline might involve them dealing with outside threats to their family. Since they are in the wizarding world, there could be dark wizards targeting them. They would have to rely on their love and magic skills to protect each other and their home. Also, they could have adventures together, like exploring new magical places that are only accessible to married wizards.
Well, a plotline might involve them facing challenges from the wizarding world. For example, there could be threats from dark wizards which they have to fight together as a married couple. Or perhaps they get involved in some sort of magical research as a team in their married life. Also, their relationship growth is a big part. They could have little arguments and then make up in the most romantic ways, like James bringing Lily her favorite flowers after a fight.
One interesting aspect could be their post - wedding adventures in the wizarding world. Maybe they go on secret missions together, using their combined magic skills. For example, they might be tasked with protecting a powerful magical artifact from dark wizards.
There could also be a plotline where their pregnancy is put in danger. Maybe there are dark forces at work in the wizarding world that target them because of their unborn child. This can create a lot of tension and drama, as they have to fight to protect their family. It can also be a way to explore the darker side of the Harry Potter universe and how Lily and James would handle such threats while being pregnant.
One possible plotline could be that James and Lily return and have to deal with the changed wizarding world. They might be shocked at how much Voldemort's actions have affected society even after his defeat. Another could be that they return to help Harry face new threats that are emerging from the shadows of the old war.
Remus Lupin would be a great addition. He's another one of James' friends. He could offer them wise advice, especially when it comes to the more difficult aspects of their relationship or the challenges of living in the wizarding world. He might also help them out during full moons.
A plotline could be that the Potter family gets invited to a very exclusive and mysterious magical event. But there are rumors that dark forces are at work there. Harry and Ginny are hesitant, but James is excited, and Albus and Lily are curious. As they attend, they find themselves in the middle of a conspiracy that they have to solve together.
One possible plotline could be that Lily and James return during the time of Harry's battle with Voldemort. Their return could give Harry new strength and hope. They might use their old magical knowledge and skills to help in the fight. Maybe they could also reunite with their old friends like Sirius and Remus, and together they form a powerful force against the Dark Lord.
In some 'Harry married Lily' fanfictions, the plot might revolve around a prophecy that was misinterpreted. Instead of Harry being related to Voldemort in the way it was originally thought, the prophecy could be related to his connection with Lily in a romantic way. This could lead to a whole new set of events where they get to know each other on a deeper level, overcome various obstacles in the wizarding society that would oppose such a relationship, and eventually get married. There could also be elements of family drama, like how James Potter would react in such a scenario, or how Harry's friends would view this relationship.
In this fanfiction, a time - travel accident could occur. Harry is sent back in time to when his parents were still alive. Lily and James initially mistake him for someone else, but as they interact, they start to sense a strange connection. Eventually, Harry reveals who he is. They then spend some time together, with Lily teaching Harry some family - specific spells, and James showing Harry some of his Quidditch moves. This encounter changes Harry's perspective on his family history and gives him newfound confidence.
One possible plot could be that Ginny discovers a time - turning device. She accidentally goes back in time and meets Lily and James. Ginny, being a big fan of the stories she's heard about them, is initially star - struck. Lily and James are a bit confused by this strange girl but soon become friendly. They could all end up having an adventure together, perhaps trying to stop a small - scale dark magic incident in Hogwarts that Ginny knows about from history books.