One possible motivation could be revenge. Pan had caused a lot of trouble in the Once Upon a Time universe. He was manipulative and had endangered many characters. Regina, who had her own history of being wronged, might have seen killing Pan as a way to protect herself and those she cared about.
Well, in the context of fanfiction, it could be a matter of redemption for Regina. Maybe she saw killing Pan as a way to atone for her past wrongs. She had been a villain in many ways, but by eliminating Pan, who was a greater evil in her eyes, she could be seen as a hero. Or perhaps it was a spur - of - the - moment decision in the heat of a battle, where she realized that the only way to stop Pan from causing more chaos was to end his life.
I'm not sure about specific fanfictions where Regina kills Pan. But you can try searching on popular fanfiction websites like Archive of Our Own. Just type in the relevant keywords and browse through the results. There might be some really interesting takes on this plot point in the fanfiction community.
Redemption is a very popular theme. Given Regina's complex character arc in the show, many fanfictions explore her journey towards redemption, how she tries to make up for her past wrongs and find a place in the world where she can be accepted and at peace.
Perhaps in a battle against a long - lost enemy from her past. This enemy could be someone she wronged deeply before her redemption arc, and they come back seeking revenge. In the heat of the battle, she gets fatally wounded. For example, if it was a powerful sorcerer she once betrayed, they might use a spell that drains her life energy.
One possible plot could be that Regina and Sydney start off as reluctant allies. Maybe they are both trying to achieve something in the town of Storybrooke. For example, they might be looking for a magical artifact that could change the balance of power. Along the way, they discover that they have more in common than they thought. Sydney might be able to see past Regina's tough exterior and understand her motives, which are often a mix of self - preservation and a longing for something she lost in the past. As they search for the artifact, they face various obstacles, like other characters who also want the item for their own purposes. This could lead to some tense moments and action - packed scenes as Regina and Sydney have to use their wits and magic (if applicable) to outmaneuver their opponents. In the end, their relationship could develop into a true friendship, or perhaps something more, depending on the direction the fanfiction takes.
In some fanfictions, Emma and Regina could develop a romantic relationship. Their complex history would add depth to such a story. They might have moments of jealousy when other characters show interest in one of them, and then have to confront their true feelings for each other.
Regina often develops from a more guarded and controlling character to a more nurturing one. As she raises Emma, she starts to let down her walls. For instance, she may begin to show more vulnerability around Emma, sharing her own past traumas.
Emma would be devastated. She and Regina had come a long way from being enemies to friends. Regina's death could make Emma question her own abilities as a savior. She might become more withdrawn at first, but then use her pain to fuel her determination to protect the town even more fiercely, knowing that Regina would have wanted it that way.
The baby could change the power dynamics. For example, if there are villains in the story, they might see the baby as a threat or a tool to gain more power. On the other hand, the heroes would want to protect the baby and its potential for good.
Snow White might be initially suspicious, given their past history. But she could also show a more empathetic side and try to help Regina. Hook might be amused and make some snarky comments at first, but then offer his protection. Rumpelstiltskin could see it as an opportunity to manipulate Regina further, perhaps by offering her magic to ensure a safe pregnancy in exchange for favors.
Family relationships are also a big theme. Her relationship with her mother Cora is a central focus in many fanfictions. Writers might explore how Cora's strict upbringing and high expectations affected Regina as a child. Also, her relationship with her father or any other family members can be a theme, showing how her family environment influenced her personality development. It's often a complex and emotional exploration of family dynamics.