At first, their relationship might start out as a simple acquaintance - type thing. Sirius sees Hermione as a smart young witch, but as he comforts her more, they start to develop a deeper bond. Maybe they start sharing secrets about their past traumas.
Often, it begins with Hermione trying to help Sirius deal with his post - Azkaban trauma. She uses her knowledge and compassion to reach out to him. As he heals, he starts to see her in a new light. Their relationship then grows as they start to understand each other better. The lemon parts usually are used to explore their more passionate and private moments, which are often written in a very tender and intense way, adding a new dimension to their relationship.
Well, in some fanfictions, their relationship starts off very rocky. Snape is reluctant at first because of his past grudges. But as he is forced to protect Hermione, he gradually sees her intelligence and bravery. He might start to respect her more and they could develop a sort of begrudging alliance. As time goes on, this could turn into a more complex relationship where they actually start to care for each other in a way neither expected.
Well, it could start with initial awkwardness. Since they come from different worlds - Hermione from the wizarding world and Bella from the Twilight world. Maybe at first they don't understand each other. But as the story progresses, they might start to find common ground in their strong wills and determination. They could end up supporting each other in their respective battles, whether it's Hermione against the Dark Arts in her world or Bella dealing with the vampire - werewolf drama in hers.
Some fanfictions show their relationship developing in a more emotional way. They might discover they have similar traumas from their pasts, which makes them bond on a deeper level. Sirius could open up to Hermione about his time in Azkaban and how he felt being wrongly accused. Hermione could share her experiences of being an outsider in the wizarding world. This mutual understanding helps their relationship grow into a strong and loving sibling bond.
Well, in many of these fanfictions, at first, Sirius is a bit wary of Hermione. He's been through a lot and isn't used to having someone so young and seemingly innocent be so involved in his life. But Hermione's determination wins him over. As they spend more time together, they start to understand each other better. Hermione learns about Sirius's past traumas and he discovers her hidden strengths. Their relationship evolves into a very strong bond, whether it's a platonic bond of friendship and mentorship or, in some cases, a romantic connection. For instance, they could be in a situation where they have to rely on each other completely to survive a dangerous encounter with a powerful dark wizard, and this experience cements their relationship even further.
At first, it might be a bit rocky. Harry is used to a more structured upbringing at the Dursleys', while Sirius is quite the free spirit. But as time passes, Sirius starts teaching Harry about his family heritage. They go on adventures together, like exploring the Forbidden Forest. Harry begins to see Sirius as a true father figure, and Sirius sees Harry as the son he never had. They also have arguments, like when Sirius is overprotective, but they always work through it, which deepens their relationship.
It could develop in a complex way. The spanking incident might initially create tension between them. Harry could be angry or resentful towards Sirius at first.
In some fanfictions, Hermione might be comforted by Sirius after an encounter with a dark wizard or a particularly difficult spellcasting session. Sirius, being a skilled wizard himself, would reassure her. He might take her on a walk around the grounds of Grimmauld Place, showing her the beauty in the old, dark place and telling her that just as the place has hidden charm, so does she, even in her moments of self - doubt.
Well, it probably strains their relationship. Sirius might feel offended and start to distance himself from Hermione. He could be less likely to trust her or cooperate with her in whatever they were doing in the fanfic.
In many fanfictions, Sirius Black might comfort Hermione by using his own experiences. For example, he could share his tales of survival against the dark forces, showing Hermione that she can also endure tough situations. He might also offer her a safe space, like in Grimmauld Place, where she can relax and feel protected.