A cool plot could be that a character time - travels to the very beginning of the SMP and tries to befriend all the original members in a different way. This might change how the groups and factions form later on. For instance, if Dream was befriended differently, it could change his whole attitude towards the server. Or, time travel could be used to explore what would happen if a dead character was brought back to life at a different point in time. How would their return affect the relationships and power dynamics? Maybe Wilbur Soot could be brought back right before the creation of L'Manberg and have a second chance at leading it in a more peaceful way.
Well, a plot idea could be a time - traveling device that malfunctions and sends multiple characters to different time periods randomly. Some might end up in the past during important historical events on the SMP, while others could be sent into the future to see the consequences of their current actions. This would create chaos as they try to find their way back to their original time. Also, a character could time - travel to meet their past or future selves. This encounter could lead to self - discovery and a change in their character arc. For example, if Tubbo met his future self, he might gain wisdom about how to handle the difficult political situations on the SMP.
One interesting plot idea could be a character traveling back in time to prevent a major war on the SMP. They could change key events and alliances, leading to a completely different SMP landscape. For example, if Tommyinnit went back to before the L'Manberg revolution, he might be able to stop Schlatt from taking over in the first place. Another idea is a character from the future coming back to warn the current SMP members about a looming threat that they don't yet know about. This could create a sense of urgency and force characters to make difficult decisions. And perhaps a time - traveling villain who is trying to rewrite history for their own gain, like stealing all the valuable resources before they were ever discovered.
A crossover with a fantasy - themed story like 'Lord of the Rings' could be amazing. Imagine the Dream SMP characters in Middle - earth. Tommy could be like a young hobbit getting into all sorts of mischief, and Dream could be a sort of dark wizard - like figure. They'd have to deal with orcs, trolls, and all the other classic LOTR threats.
A cool plot might be that the BNHA villains discover the Dream SMP and see it as a new place to expand their evil plans. They kidnap some of the SMP members thinking they can use them for something. The SMP members then team up with the BNHA heroes to fight back. Techno could use his combat skills and the BNHA heroes would be amazed at his fighting style without having a Quirk. And the SMP members could learn about the importance of working as a team like the BNHA heroes do.
I think Fundy would be likely to time travel. He has a complex relationship with his family and the SMP. Time travel could be a means for him to understand his father better or change the way his family relationships developed. GeorgeNotFound could also be a candidate. He's often in the background but has a strong connection to Dream. Time travel might be his way of getting more involved in the SMP's events and helping Dream in a different way. Lastly, Niki could be a time traveler. She has been through a lot of changes on the SMP, and time travel could be her opportunity to go back and make the SMP a more inclusive and friendly place from the start, especially for those who have been marginalized.
One idea could be Madara traveling back to the era of the Sage of Six Paths. He could try to change the very foundation of ninjutsu, which would create a whole new timeline. Maybe he would attempt to gain the power of the Sage for himself much earlier in history.
Well, perhaps a time - traveling device accidentally sends Judy Hopps back to a time when prey and predator relations were extremely tense. She has to use her wits and modern - day knowledge to prevent a major conflict that could have changed Zootopia's future for the worse. Or, a time - traveling fanfiction could focus on Nick Wilde going back to his own past, where he can make different choices that would impact his relationship with Judy and his standing in Zootopia society in the present.
One idea could be a character from the present in BO2 traveling back to a crucial moment in the game's history to change the outcome of a major battle. This would create a whole new timeline and a lot of interesting interactions with past characters.
Perhaps they travel forward in time instead. They could see the consequences of their actions in the future. Maybe they find out that their actions had unintended negative effects on some of their friends or the city as a whole. This would lead them to go back and try to fix things in a different way.
One idea could be Sauron travels back to the time before the forging of the Rings of Power. He could try to prevent the elves from ever having the knowledge to create such powerful items, thus changing the course of Middle - earth's history in his favor. Maybe he would target Celebrimbor directly, the elf - smith who was crucial in the creation of the rings.
In some narusasu time travel fanfiction, Naruto might go back to the time when Orochimaru was first targeting Sasuke. He could then use his skills and knowledge to keep Sasuke safe and away from Orochimaru's influence. A different plot could be Sasuke traveling to a time when Naruto was ostracized as a child and being the one to support Naruto, which would change their relationship dynamic from the start. Also, they could travel to a time during a major battle and use their combined future knowledge to turn the tides in their favor.
Another plot could involve Merlin traveling to the future. He might see a desolate Camelot, destroyed by some unknown force. Then he has to return to his own time and figure out how to prevent this dark future from happening. This would involve him using his magic in new and creative ways to influence the present to change the future.