Castiel, the angel, is also a common character in such scenarios. He has his own reasons to want Lucifer punished. As an angel, he stands for the good in the 'Supernatural' universe and Lucifer represents the ultimate evil. Castiel might use his angelic powers to assist in Lucifer's punishment, or at least be part of the group that decides on the punishment.
Definitely Sam and Dean Winchester. They are the main protagonists in 'Supernatural' and have a long - standing feud with Lucifer. They've fought him numerous times and would be the most likely to be involved in his punishment. Their motivation would be to protect the world from Lucifer's evil plans.
Chuck, or God in the 'Supernatural' series, could also be involved. Since he is the creator, he has the power to dish out punishment to Lucifer. He might decide to finally put an end to Lucifer's reign of terror by imprisoning him or taking away his powers completely. His involvement would add a whole new layer of complexity to the fanfiction as it would bring in the aspect of divine justice.
Sam Winchester is quite popular to pair with Lucifer. Their connection in the show, with Sam being one of Lucifer's vessels, makes for an interesting dynamic in fanfiction. Also, Castiel. The angel's moral compass and his power contrast well with Lucifer's nature.
One popular storyline could be Lucifer being punished for his past deeds by the main characters in the 'Supernatural' universe. For example, Sam and Dean might use some powerful magic or a special weapon to confine Lucifer and make him suffer for all the chaos he has caused. They could send him to a desolate dimension where he has to endure constant pain as a form of punishment.
In some fanfictions, Lucifer might be punished by being trapped in a desolate dimension. This is often a way for the writers to show that even a powerful being like him can't escape justice. For Crowley, he could be punished by losing his demonic powers. It makes sense as his powers are a big part of what makes him a threat in the Supernatural universe.
Perhaps a fanfiction where Lucifer and his brothers are forced to team up against a common enemy much stronger than any they've faced before. During this time, they have to put aside their differences and learn to trust each other again, leading to some heartfelt moments and character growth for all of them.
The main character would be the daughter of Lucifer. Depending on the plot, other important characters could include some of the powerful demons who might be trying to control or use her. Also, there might be some human characters who get involved with her story, perhaps a hunter who initially wants to kill her but then realizes she's not all bad. And of course, Lucifer himself might make appearances to influence his daughter's actions.
A common theme is the battle between good and evil. In both Supernatural and Lucifer, this is a central concept, and fanfictions often explore it further. For example, how characters are tempted by evil or strive to do good in difficult situations.
One of the popular pairings is Michael/Lucifer themselves. Their complex relationship, being brothers and eternal rivals, lends itself well to shipping in fanfiction. Writers like to explore the dynamic of their love - hate relationship in a romantic or at least very intense emotional context.
Definitely Natsu. He's always getting into trouble with his brash actions, so he's a prime candidate in punishment scenarios. Then there's Lucy. She's new to the guild in a way and still learning the ropes, so she could easily find herself on the receiving end of a punishment. And of course, Makarov, as the guild master, is often involved in doling out or dealing with punishments for the members of Fairy Tail.
The other Slytherin students are very likely to be involved. Some might side with Draco, while others might see his punishment as an opportunity to gain power within the Slytherin hierarchy. Pansy Parkinson, for instance, might react in different ways depending on her relationship with Draco at the time of the punishment.
Often, the characters that are the best - written are those that are given a new perspective in the fanfictions. For example, a fanfiction might show Lucifer as a victim of circumstance rather than just a pure villain. This new take on his character can make him very interesting. Similarly, Michael can be written in a way that shows his vulnerability, perhaps his doubts about his actions in the name of order. When these complex aspects are explored, they can become the best - written characters in the Supernatural Lucifer and Michael fanfiction.