A scenario could be that the 10th walker has been following the fellowship secretly in Moria. When they finally reveal themselves, the fellowship is shocked. If the 10th walker is a skilled healer, they could tend to the wounds of the fellowship members who got injured in the mines. Or, the 10th walker might be a wizard with powers different from Gandalf's. Their magical abilities could either be a great asset or cause some unease among the fellowship.
The encounter of the 10th walker with the fellowship at Moria in fanfiction can be very interesting. The 10th walker may bring a new dynamic to the group. Maybe they are from a different race or culture that the fellowship has not encountered before. This could lead to cultural exchanges within the group. For example, they might have different ways of fighting or different beliefs about the dark forces in Moria. Their presence could also change the power balance within the fellowship, either causing some tension or strengthening the group as a whole. They might have a special connection to the ancient magic of Moria, which could be crucial in helping the fellowship overcome the many obstacles they will face in that dark place.
One possible plotline is that they meet in a time - locked situation. They have to work together to break the time lock. Another could be that they meet because of a shared enemy that has somehow found a way to target both of their timelines. They would then have to put aside their differences and use their individual strengths to defeat the enemy.
Another plotline could be that the immortal has some knowledge that the Doctor needs. The Doctor is constantly seeking knowledge, and the immortal, having lived for so long, might hold the key to solving a big problem in the universe. So the Doctor has to convince the immortal to share that knowledge, which might not be easy as the immortal could be very guarded about it.
A storyline could involve a character from Torchwood getting trapped in a time loop. The 11th Doctor shows up and, with his knowledge of time mechanics, tries to break the loop. Along the way, he gets to know the Torchwood team better and they learn a great deal from him about the nature of time and the wider universe.
In a fanfiction plot, Yusei might meet his dad in a completely unexpected place, like in a different dimension. His dad has been trapped there for a long time. Yusei tries to find a way to get his dad out. Along the way, they share their stories, their hopes and dreams. Yusei realizes that his dad is not the person he thought he was, and his dad is also amazed by how Yusei has grown up. They finally manage to escape the dimension together and start a new life together.
One possible scenario is that the fem gymnastics reader might initially be really creeped out. Since creepypasta often involves disturbing and horror - related content, it could be quite a shock for someone used to the elegance and athleticism of gymnastics. For example, if she stumbles upon a particularly gory or psychologically disturbing creepypasta fanfiction, she might feel disgusted or even a bit scared.
Maybe they meet in a forest. The Warden could be traveling through when they come across Zevran, who is hiding from some pursuers. The Warden decides to help Zevran out, and during this time, they catch up on what has happened. Zevran could tell the Warden about his attempts to leave his old life as an assassin behind and start anew, while the Warden might talk about the new threats emerging in the post - Blight world.
Perhaps they find themselves in a situation where they have to rescue a group of people trapped in a parallel universe. Jack's skills as a former Time Agent and the Doctor's ability to navigate difficult situations would be crucial in this rescue mission. It could also be a chance for them to learn more about each other's pasts and grow as characters.
One interesting scenario could be the 11th Doctor and Rose exploring a new and strange planet together. They might encounter unique alien species that test their wits and courage. Another could be a moment of emotional reunion, where the Doctor realizes how much he has missed Rose during his different regenerations.
One scenario could be that they meet in a college setting. Rick could be studying criminal justice and Michonne could be pre - law. They meet in a study group or at a campus event.