It could be set in a post - war scenario where the lines between former enemies and allies are blurred. Hermione is researching some dark magic that Severus has knowledge of. As they spend long hours together in the library or some secret chambers, they start to see each other in a different light. One night, after a particularly intense discussion about magic and the past, emotions run high and they end up having a one - night stand. But then they have to decide whether to forget it ever happened or explore if there could be more to their relationship.
One possible plot could be that they are forced to work together on a very dangerous and urgent mission. In the midst of the high - stress situation, there is an unexpected moment of intense connection that leads to a one - night stand. But afterwards, they both struggle with the implications and how it fits into their existing views of each other and the wizarding world around them.
In fanfiction, anything can be made plausible. However, Hermione and Lucius come from very different sides in the Harry Potter universe. Hermione is a Gryffindor, representing courage, justice, and friendship, while Lucius is a Death Eater, associated with dark magic and evil. A one - night stand between them would be highly uncharacteristic based on their original traits. But fanfiction often takes creative liberties to explore 'what - if' situations, so some authors might write it to show a radical departure from the norm or to explore complex power dynamics and character transformations.
One possible plot development could be the aftermath of the one - night stand. Hermione might be filled with guilt and confusion, given her values and the fact that Lucius is on the 'enemy' side. Lucius, on the other hand, could be intrigued by Hermione's different nature and try to draw her further into his world, leading to a battle of wills between them.
Their relationship could turn into a bitter rivalry again. Maybe they both regret the one - night stand immediately. Hermione might think Severus took advantage of her in a moment of weakness, and Severus might think Hermione was just being a silly Gryffindor. This would cause them to start arguing and competing again, but this time with an added layer of personal animosity from the night that they shared.
Fanfictions with this plot usually delve deep into the emotions of the two characters. Hermione, being the logical one, might start making plans right away for the future. Draco, on the other hand, could be more hesitant. The pregnancy could be a catalyst for them to overcome their differences. It could also lead to a lot of conflict, especially if the wizarding world at large gets involved. Their families and friends might have strong opinions, which adds to the drama and tension in the story.
One possible plot could be that Hermione, in her intelligent and empathetic way, sees the pain and complexity within Severus. She gradually breaks through his cold exterior. For example, in a Hogwarts setting post - war, Hermione might be researching some dark magic remnants and Severus, with his in - depth knowledge, becomes an unexpected ally. Their relationship could start as a mutual respect for each other's minds and then develop into a deeper, more romantic love as they spend more time together, defying the expectations of the wizarding community.
One idea could be that it leads to an unexpected pregnancy, which then forces Draco and Hermione to re - evaluate their relationship. They might start out being very confused and conflicted, but as time goes on, they begin to see each other in a new light and work towards building a more stable relationship for the sake of the baby.
One possible plot twist could be that the baby has some unique magical abilities that neither Severus nor Hermione expected. Maybe the baby can communicate with magical creatures in a way no one has seen before. This could lead to all kinds of adventures as they try to understand and control this new ability.
Maybe in a time - travel fanfiction. Hermione travels back in time and ends up in Snape's student days. She tries to change some events for the better, and in the process, she gets to know a younger Snape. Their interactions are initially rocky but gradually turn into something more, leading to a kiss. This would be a very different take on their relationship, as it involves a different time period and different versions of themselves.
It could be that the dream is a premonition of some sort. Severus and Hermione start to notice similarities between the events in the dream and things that are starting to happen in the real world. They then try to use the knowledge from the dream to prevent a disaster from occurring. This would involve them relying on each other's skills and knowledge, and growing closer as a result.
I don't really support the idea of Harry and Hermione having a one - night stand in fanfiction as it goes against their established relationship in the original series. However, there may be some out there. You could try searching on some major fanfiction websites like Fanfiction.net or Archive of Our Own, but be aware that such content might not be in line with the spirit of the original books.