One possible plot could be that Harry and Snap are facing some sort of danger in Britain, perhaps from dark wizards or a corrupt magical government. So they decide to flee. They might embark on a journey to find a safe haven, like a hidden magical community in another country. Along the way, they encounter various challenges and make new friends who help them in their quest.
Maybe Harry and Snap flee Britain because they are wrongly accused of a crime they didn't commit. They have to leave quickly to avoid being caught. They start by using magic to disguise themselves and then use a secret portkey to get out of the country. Once they are out, they struggle to find a place where they can live without constantly looking over their shoulders. They end up in a small wizarding village in France where they slowly build a new life while trying to clear their names.
Well, clearly Harry and Snap are the main characters. Harry is likely a well - known character, perhaps from the Harry Potter universe. As for Snap, not sure if it's a new character created specifically for this fanfic or a less - known character from the existing lore. Maybe Snap is Harry's friend or a mentor - like figure, and together they are the focus of the story as they flee Britain.
In fanfiction, Harry could flee Britain due to a sense of disillusionment with the wizarding world there. He has been through so much trauma and has seen the flaws in the system. For example, the way the Ministry handled the threat of Voldemort in the past was often inept. He might also be seeking a place where he can explore magic in a different way, free from the traditional constraints of the British wizarding community. He may want to start anew in a place where no one knows him as 'The Boy Who Lived' and can just be Harry, an ordinary wizard exploring his magical abilities.
One possible plot could be that after some time away, Harry has gained new skills or knowledge. Britain is facing a great threat, perhaps a magical one if it's in a wizarding world context. The people realize that Harry is the key to solving the problem, so they try to convince him to come back. They might send his old friends to persuade him, and he has to decide between his new life and his old homeland that now needs him.
Well, perhaps in this fanfiction, Harry Potter accidentally casts a spell that has a domino effect on the magical economy of Britain. For example, he might mess up a powerful charm related to the wizarding currency, leading to a rapid devaluation. Or maybe he uncovers some dark secret about the Ministry of Magic's financial management that causes a mass panic and economic collapse.
I'm not sure specifically as there could be many different interpretations of such a fanfic. It might be about Harry and Severus having to flee after an encounter with Quirrell. Maybe there's some sort of danger that Quirrell poses, and they have to run away to save themselves or for some greater purpose in the wizarding world.
The plot might involve Grindelwald coming to Britain to recruit followers for his cause. Phosphene could be a symbol or a power source that he believes will help him achieve his goals. Tom Riddle, being a Slytherin and already showing signs of his dark nature, is approached by Grindelwald. However, Tom has his own plans. He wants to use Grindelwald's knowledge and Phosphene's power to rise to the top on his own terms. So, he plays a double - game, pretending to be a loyal follower while secretly plotting against Grindelwald.
One reason could be the media attention. After all they've been through, they might be tired of constantly being in the spotlight. The British wizarding press could be hounding them, so they leave to get some privacy.
One possible reason could be to seek new opportunities. In fanfiction, the States might be depicted as a place full of exciting prospects in various fields like magic (if it's a Harry Potter - related fanfic) or just in general life. For example, he could be interested in exploring different magical cultures there.
One reason could be to escape the constant reminders of his past traumas in Britain. The place is filled with memories of Voldemort and the battles he fought. Maybe in the fanfiction, he just wants a fresh start away from all that chaos and danger.
One possible plotline could be Harry using magic in creative ways to evade the authorities as he escapes. For example, he might use a complex series of apparition spells combined with disillusionment charms.