On the other hand, Sam might be a bit skeptical of her return at first. He's seen a lot of strange things in the world of Supernatural, and he might wonder if this is really Jessica or some kind of trick. This could create an interesting dynamic as he tries to figure out the truth about her return.
Another theme is the idea of redemption. Some fanfictions have Jessica coming back in some way, and Sam sees it as a chance to make things right, to protect her better this time. It's like he gets a second chance at their relationship, which ties into the whole redemption concept in the Supernatural world.
Perhaps Jessica returns but she has some sort of new power. For example, she might be able to see the future or has a connection to the other side that helps the Winchester brothers in their hunts. This could be a really interesting twist in the fanfiction.
If Jessica lives, Sam would be less driven by revenge. His initial motivation to hunt was mainly because of her death. So, he might be more hesitant to jump into dangerous situations. He could focus more on protecting Jessica and building a normal life with her, which would be a huge shift from his vengeful and nomadic hunter life.
In some fanfictions, Sam tells Jessica about hunting when she starts to notice strange things around her. This often leads to a series of events where Jessica discovers her own hidden abilities related to the supernatural world. It's an interesting take as it gives Jessica a more active role in the story rather than just being a bystander to Sam's life.
A good one should have a believable reaction from Jessica. Since she's a normal person being thrust into this crazy world of hunting, her shock, confusion, and then acceptance (or not) need to be well - written. For example, she might initially think Sam is crazy but then see evidence that makes her change her mind.
One great 'Sam and Jessica Supernatural fanfiction' is 'Sam's Lost Love'. It delves into Sam's memories of Jessica and how it affects his actions in the hunting world. It's a really emotional piece that shows his internal struggle.
Naruto would be overjoyed to see his parents. Emotionally, it would give him a great boost. He would finally have the family he always dreamed of having around him.
For Ruby, Pyrrha's return could be a huge boost in morale. Ruby has always looked up to Pyrrha, and having her back would give Ruby more confidence in their fight against the Grimm. Weiss might be a bit more skeptical at first, but eventually warm up to Pyrrha again as she realizes how much they need her. Blake could see Pyrrha as a symbol of hope and a reminder that they can come back from difficult situations.
Harry would likely be overjoyed at first. After all, he never really got to know his parents. Their return could give him a sense of family and belonging that he's always craved. It could also help him deal with some of his past traumas, having his parents there to support him.
Dean would probably be very protective. He's always been the big brother looking out for Sam, and with Sam as a kid, that instinct would be even stronger. He'd be constantly worried about Sam getting hurt and would keep him close at all times.