If Arya becomes the Night Queen, her personality might become more cold and calculating. She has always been a survivor, but as the Night Queen, she would need to be more ruthless to control the White Walkers. Her sense of humor and playfulness might disappear as she takes on this dark and serious role.
Arya's personality could change drastically. She has been a character who values justice and family. But as the Night Queen, she might start to see things from a more detached perspective. She may become more solitary, as the power she wields might isolate her. Her once warm relationships could turn into ones of fear or respect. For instance, she might not show the same affection towards her siblings. Instead, she would be focused on her new duties and the power she holds over the dead and the living. She could also become more patient, as she has an eternity to plan her moves, unlike when she was just a human assassin.
Her relationships would become more complex. Her family might not recognize her at first, and when they do, they might be afraid. Her friends could be both in awe and a bit scared of her new identity.
If Arya Stark becomes the Night Queen in a fanfic, it would be quite a shock to the system. Arya has always been a fighter against the forces of darkness, so her becoming the Night Queen would be a complete role reversal. One possible plot could be that she is forced into this position against her will, perhaps by some ancient magic or a deal gone wrong. Then, she has to navigate her new identity while still holding on to some of her old values, which could lead to a lot of internal conflict.
She might use her new role to bring justice in a different way. Maybe she'd secretly punish the corrupt nobles who escaped regular justice. The Stranger is often associated with death and the end, so Arya could be the one to end the reigns of tyrants in the fanfic world.
As Queen of the North, Arya's character would transform significantly. Her wild and independent streak would still be there, but she'd learn to channel it in a more productive way. She'd start to understand the importance of traditions and how they can be used to unite the people. Her relationship with power would be complex. On one hand, she'd use it to protect the North, but on the other, she'd be cautious not to let it corrupt her. She'd develop a more regal presence, but still keep her roots as a Stark. Her skills as a spy and assassin would be used in more strategic ways, like uncovering plots against the North and eliminating threats without causing unnecessary chaos. And she'd have to learn to balance her personal desires with the needs of her kingdom.
His positive and determined personality would turn into a cynical and cruel one. He might lose his sense of justice and become self - centered.
His sense of responsibility would likely increase even more. Harry has always been responsible, but as a priest, he would feel accountable for the spiritual well - being of others. He would become more solemn and less impulsive perhaps. His Gryffindor impulsiveness might be toned down as he takes on a more serious religious role.
Arya's character might develop in terms of her leadership skills. From being a lone wolf, she has to become a leader. She'll learn to make decisions for the greater good of Winterfell, not just for her own survival.
Arya could encounter old friends like Gendry. Their relationship might have evolved during her time away, and there could be new feelings or just a strengthened bond of friendship. Also, she may come across some of the younger Stark bannermen who have grown up in her absence and now look up to her as a hero.
Arya's identity as a Stark would be more deeply ingrained in her. She would start to embrace all the values that the Starks stand for. She might even try to teach these values to the people of the North. Her development would also involve her coming to terms with her past as a Faceless Man. She would decide how much of that part of her should be part of the new Stark legacy she is building.
She might become more confident in public. As a model, she has to be in the spotlight a lot, so she would likely grow out of her shyness. For example, on the runway, she'd need to strut with confidence.