Snape's character changes in multiple ways. He may become less bitter. His loyalty to Dumbledore and the cause of fighting Voldemort becomes more about doing the right thing rather than just revenge. He also tries to build better relationships. In some fanfictions, he reaches out to Harry and tries to explain himself, which is a huge change from his aloof and often hostile behavior in the original books.
In these fanfictions, Snape often becomes more self - reflective. He starts to realize the full extent of his actions and how they've affected others. For example, he might come to see how his treatment of Harry was unfair. He also becomes more open about his emotions, which was something he always hid before.
In Severus Snape redemption fanfiction, his character transformation is quite profound. He moves from a character full of anger and resentment, especially towards James Potter and by extension Harry, to one who is seeking forgiveness. He starts to show more kindness and understanding. His actions are no longer solely driven by his love for Lily in a possessive way but by a desire to truly make the wizarding world a better place. He may even start to mentor younger witches and wizards, using his vast knowledge for good rather than just to intimidate students as he did at Hogwarts.
Snape's character changes in his relationship with others too. He becomes more involved with the Hogwarts community as he is now responsible for Harry. He might start to collaborate more with other teachers, like McGonagall, who he previously had a rather cold relationship with. His attitude towards the students also changes as he realizes that they are just kids trying to find their way, much like Harry. This is a big shift from his usual strict and often unforgiving self.
Snape's character often becomes more open - minded. In many such fanfictions, being around the Marauders, who are generally more carefree and adventurous, forces Snape out of his shell. He starts to see things from different perspectives, rather than just being the brooding loner he was originally.
In terms of appearance, a female Snape would look different, of course. But more importantly, her self - confidence might be presented in a different way. A female Snape could use her appearance and charm in a way that the male Snape never did, to manipulate situations or gain allies, which would be a significant change from the original character.
In some fanfictions, Severus Snape's character develops by becoming more open - minded towards Muggles. He might start off with his typical wizarding - world prejudices, but through various interactions, he begins to see Muggles in a new light. For example, he could meet a Muggle scientist whose thirst for knowledge reminds him of his own love for potions, and this changes his view.
She could also be more perceptive of social hierarchies in a different way. Girls in the wizarding world might be subject to different expectations. Snape as a girl might use her femininity to her advantage, perhaps by being more charming or manipulative in certain situations to get what she wants, which is different from the male Snape's more brooding and solitary approach.
Snape's personality would likely soften. He'd have to be more patient and understanding. Instead of just being the strict and often sarcastic Potions master, he'd become more nurturing. He'd still have his sharp edges, but around Harry, he'd show more kindness and care as he takes on the role of a guardian.
The re - imagining of Snape as trans in fanfiction can also play with the idea of how magic could interact with his gender identity. For instance, could there be spells or potions that are more difficult for him to use because of his trans identity? Or perhaps there are magical ways to help him transition that are unique to the wizarding world. His role as a Potions master could also be tied into this, like creating new potions related to gender transition or using his knowledge to help other trans wizards in the fic.
It could make him more confident. Just the fact that he has a connection with Snape through the portrait might boost his self - esteem.
In romantic relationships in fanfiction, Snape can be quite badass. He might be very guarded at first, not easily giving in to his feelings. But when he does, he's all in. He'll protect his love interest from any danger, whether it's from dark wizards or from the prying eyes and gossiping tongues of Hogwarts. He uses his skills and knowledge to keep them safe, and if anyone tries to come between them, he'll use his wit and magic to drive them away.
It changes the power dynamics. Usually, Snape is seen as an outcast and Hermione is part of the main group. When she trusts him, it gives Snape more of a connection to the 'good side'. For example, the other characters might start to re - evaluate their views of Snape because Hermione trusts him.