One common way is by giving Snape hope. Dumbledore could talk about the end of Voldemort's reign and how Snape's part in it is essential. For instance, he might say that Snape's knowledge and skills are the keys to victory. Another way is by showing trust. Dumbledore might entrust Snape with more important tasks or secrets, which makes Snape feel valued.
In many such fanfictions, Dumbledore might comfort Snape by reminding him of his good deeds. For example, he could say that Snape's role as a double agent is crucial for the greater good. Dumbledore might also offer a sympathetic ear, listening to Snape's inner turmoil about his past actions and his love for Lily. By validating Snape's feelings and his importance in the fight against Voldemort, Dumbledore provides comfort.
Well, perhaps one of the other teachers might have noticed Snape's behavior towards Harry and reported it to Dumbledore. It could also be that Dumbledore, being as perceptive as he is, noticed Snape's extra harsh treatment of Harry during their interactions in the corridors or in class.
I really like 'Snape and Dumbledore: A Hidden Alliance'. It presents a unique take on their relationship, exploring how they worked together behind the scenes to protect Hogwarts. It has some really interesting character interactions and a well - crafted plot.
In the fanfiction, Snape could protect Harry from Dumbledore by using his skills in potions. For example, he might create a potion that hides Harry's magical signature from Dumbledore's detection. Or he could use his knowledge of the Dark Arts to counter any spells or charms that Dumbledore might use to keep tabs on Harry. Snape is very intelligent and resourceful, so he could find various ways to physically and magically shield Harry from Dumbledore.
Maybe he notices Harry's unusual behavior, like being overly withdrawn or flinching at sudden movements. That could be a sign that makes Dumbledore suspect abuse.
Another possibility is that the main antagonist could be some sort of ancient evil that is awakened by the events in the fanfic. Dumbledore might have given Snape to Harry because he sensed this new threat. This ancient evil could have powers that are unknown to the modern wizarding world and it would be up to Harry and Snape to figure out how to defeat it.
Yes, there are some fanfictions with this rather interesting concept. In the world of Harry Potter fanfiction, authors often like to explore alternative family relationships. It can make for a very different take on the original story, exploring how Snape's character would be different if he were Harry's father and how that would impact Harry's upbringing and his relationship with other characters in the wizarding world.
Yes, there are likely fanfics out there involving Tom Snape (assuming this is an original character in the fanfic world) and Harry's father. Fanfic writers often create unique and interesting scenarios with different character combinations.