One common theme is redemption. The idea that voldenort can be redeemed through his relationship with Harry. It gives a new perspective on his character.
There's also 'The Unlikely Bond'. This fan fiction explores how voldenort's decision to adopt Harry changes the course of the entire wizarding war. It has some great character development for both voldenort and Harry as they navigate their new relationship.
One possible plot twist could be that Voldenort adopts Harry with the intention of turning him into a dark wizard, but Harry's inherent goodness starts to change Voldenort instead. Maybe Harry shows Voldenort kindness that he has never experienced before, leading to a shift in Voldenort's character.
I'm not sure about specific fan fictions with this exact plot. But you can try searching on fan - fiction - specific websites like Archive of Our Own or FanFiction.net. Just use the keywords 'Voldenort adopts Harry from Dursleys' in their search bars.
You can start by looking on fanfiction.net. It has a large collection of Harry Potter fan fictions, and there are likely quite a few 'Snape adopts Harry' ones in there. Just use the search function and type in the relevant keywords.
One common theme is redemption. Severus, who has had a complex and often negative relationship with Harry in the original series, gets a chance to redeem himself by protecting and caring for Harry. It shows that he can be more than just the strict and often cruel teacher.
In this fan fiction, Harry's development is likely to be quite different from the original series. He may start to question the black - and - white view of good and evil he had before. With Snape's intervention in his life, he might see the complexity of people more clearly. At Bloor's, he'll be exposed to a diverse range of characters and situations. This will force him to grow up faster and become more adaptable. He may also develop a more in - depth understanding of magic as Bloor's might have different magical traditions than Hogwarts, and he'll have to learn and adapt to them.
In this fan fiction, Snape might adopt Harry because he realizes that Harry has a lot of potential that is being stifled at the Dursleys. He could take Harry to a secret location and train him not only in magic but also in self - defense and survival skills. Snape would have to deal with his own complex feelings towards Harry, as he has both resentment and a sense of obligation. And Harry would have to adjust to living with Snape, who is not exactly the warmest person. It could be a story of growth and understanding between the two.
In this fan fiction, Snape could save Harry from Voldemort's followers who are after him. The blood adoption might be a way to give Harry a new family connection. Snape, having complex feelings for Harry's mother, might see this as a way to fulfill a promise or a way to atone for past actions. He could then teach Harry some of his more advanced potions knowledge and help him develop his occlumency skills better.
One popular one is 'A Father's Love'. In this fanfic, Severus discovers Harry's abuse and takes him under his wing. He teaches Harry potions and helps him deal with the trauma of his past in a very heart - warming way.