A great plot could be that a new threat emerges that targets both magic - users and mutants. Harry and Logan are brought together by a mutual acquaintance who believes that their combined abilities are the key to stopping this threat. Along the way, they learn from each other's worlds, with Harry teaching Logan about magic spells for protection and Logan showing Harry some of his survival and combat techniques.
One idea could be that Harry has a unique mutant power that Logan initially misunderstands. For example, Harry might be able to manipulate time in small increments, which Logan mistakes for some form of trickery at first. Another could be that they team up to rescue a group of young mutants from a powerful anti - mutant organization. They would have to combine Logan's combat skills and Harry's strategic thinking to succeed.
One idea could be that Logan is initially shocked but then becomes extremely protective. He starts preparing a safe haven for Rogue and their unborn child, like fixing up an old cabin in the woods. He gathers supplies and makes sure no one can harm them.
Maybe in the fanfiction, there's a school competition where Zoey and Logan are on opposing teams at first. But then they realize that there's some cheating going on within the competition and they team up to expose the truth. Along the way, they discover that they have more in common than they thought, like their love for justice and fairness.
One idea could be that Deadpool and Logan team up to take on a powerful new mutant threat. Deadpool's wacky humor and Logan's brooding strength would make for an interesting dynamic as they face this danger together.
Well, perhaps in the fanfiction, Logan could be really over - protective of Veronica during the pregnancy. He might hire a whole team of security for her. And Veronica, being the independent person she is, might struggle with this at first. Also, they could have a storyline where they start preparing the nursery and they have different tastes in decoration. Logan wants something super luxurious while Veronica wants a more practical and simple design.
One plot idea could be that Rogue and Logan discover their baby has a unique mutant ability that they need to protect from a group that wants to use it for evil. Another could be the baby getting lost in a dangerous mutant - friendly area and Rogue and Logan have to search for it while facing various challenges along the way. And a third idea might be that the baby is sick and they have to find a cure, which leads them to explore different parts of the mutant world they've never been to before.
One idea could be that Veronica and Logan are new parents and they struggle with the lack of sleep. They have to learn how to take care of the baby while also dealing with their own relationship issues. For example, Logan might be worried about providing enough for the family financially, and Veronica has to balance her career aspirations with motherhood.
One plot idea could be that Princess and Logan are forced to team up to save Albion from a new, unseen threat. Maybe a dark magic has started to corrupt the land and they have to put aside their differences. They start off distrusting each other but as they face challenges together, they begin to understand each other's motives better.
A possible plot for 'old man logan crossover fanfiction' is a crossover with the Fantastic Four. Old Man Logan could end up in their Baxter Building and get involved in one of their scientific experiments gone wrong. He might have to use his combat skills to help them fix the situation. Another idea is a crossover with Hellboy. Logan and Hellboy could team up to fight some supernatural demons that are causing chaos in both their worlds. Also, a crossover with the Teenage Mutant Ninja Turtles could be really fun. Logan could teach the turtles some new combat moves while they introduce him to the sewers and their unique way of life.
One idea could be that Logan, a commoner in the world of Fable 3, saves the princess from a dark magic spell. As he breaks the spell, they start to have a connection. He then accompanies her on a journey to restore peace to the kingdom which has been ravaged by the aftermath of the spell. Along the way, they face challenges that test their relationship and grow closer.