Well, perhaps it's the power of character development in fanfiction. The writer might have crafted a scenario where Draco and Harry are forced to work together. As they interact more, Draco reveals his more empathetic and protective nature towards Harry, making Harry feel safe.
One reason could be that in fanfiction, the relationship between them is re - imagined. They could share a deep emotional bond that goes beyond the traditional enmity. Draco might be written as someone who truly understands Harry on a level that others don't, which gives Harry a sense of safety. He could be a source of comfort when Harry is facing difficult situations in the wizarding world.
In some fanfictions, it could be because Draco shows a different side of himself. Maybe he protects Harry from other threats secretly. For example, he might use his knowledge of the Slytherin world to keep Harry out of danger.
In some fanfictions, it could be that the author has rewritten Snape's character in a more approachable way. Maybe Snape shows a side of himself that is protective towards Harry, like secretly guiding him in his magic studies without the usual harshness, which makes Harry feel safe.
Percy is very brave. He doesn't hesitate to jump into dangerous situations, and Annabeth knows that he'll protect her. So his courage makes her feel safe.
Well, it could be that the fanfiction author has created a unique backstory. For example, Snape could have saved Hermione's life at some point in the past, and she now has this deep - seated sense of security around him. Also, he might be a source of knowledge for her, and his presence, while initially intimidating, becomes reassuring as she realizes he won't let harm come to her in matters related to magic and the school.
One common scenario is when they are in a dangerous situation together, like facing a powerful dark wizard. Draco steps up and uses his skills and knowledge to keep Harry safe. For instance, in a fanfic where they are trapped in a haunted castle, Draco uses his Slytherin cunning to find an escape route for both of them, which makes Harry feel protected.
Perhaps it's because Snape is a complex character in the original story. Fanfictions might explore his character in ways that make Hermione seem protected in those fictional scenarios. For example, some fanfictions could depict Snape using his knowledge and power to shield Hermione from various threats within the magical world they inhabit.
Well, in fanfic lore, Jasper is often depicted as a protector. He has a lot of experience and combat skills. Bella could feel safe around him because she knows he can defend her from any threats. Also, his loyalty to his family and friends might make Bella trust him more, and thus feel safe.
Maybe Harry has seen a different side of Draco that others haven't. He could have realized that Draco was just a product of his upbringing and the difficult situation he was in.
One possibility is that the fanfic changes Snape's backstory to make him more sympathetic. Harry, being empathetic, then feels safe around him. For instance, if Snape's past is shown to be full of hardships that made him act the way he did, Harry might understand and feel safer in his presence.
One reason could be that Hermione is written as a perfectionist in fanfictions. So when Harry makes even a small mistake, like mispronouncing a spell or getting a basic fact wrong about the wizarding world, she might give him a look or make a comment that makes him feel inferior. It's not always intentional on her part, but her high standards can have that effect on Harry.
In some fanfictions, Draco might brush Harry's hair as a sign of a newfound closeness or a different kind of relationship developing between them. It could be a moment of tenderness in a story where their traditional rivalry has transformed into something more affectionate.