8th doctor

One possible plot could be that during the regeneration process of the 9th Doctor, something goes awry with the Time Lord's normal regeneration cycle. Maybe there's interference from an outside force, like a powerful alien entity that wants to disrupt the natural order. This interference causes the regeneration to skip a few incarnations and directly jump to the 11th Doctor. The new 11th Doctor then has to deal with the after - effects of this abnormal regeneration. He might have some strange memories or abilities that are a mix of what the 9th Doctor was supposed to pass on and some new, unexpected elements.

They could also meet in a time - locked situation. The 12th Doctor is trying to solve a mystery from his past, and the 13th Doctor stumbles upon the same situation in her present. At first, they don't understand how they are both involved, but as they start to piece things together, they discover that it's all part of a much larger, more sinister plot. Along the way, they might meet some old friends or foes from their respective tenures as the Doctor. And in the end, they work together to outwit the mastermind behind the plot, all while having some really interesting conversations about their experiences as the Doctor.

They might have a friendly competition. For example, who can solve a time - related mystery faster.

In some fanfictions, the 10th and 11th Doctor are brought together by a time anomaly. They are forced to cooperate to fix it, and along the way, they encounter old friends and enemies. The contrast between the 10th's more traditional style and the 11th's more zany approach creates interesting dynamics. They might also have to deal with the consequences of their previous actions in different timelines, which adds an extra layer of complexity to the story.

In the fanfiction, the 11th doctor, with his eccentric and energetic personality, could initially be a bit confused by the 13th doctor's more modern approach. But then they could start to combine their wits. For example, the 11th doctor's knowledge of ancient alien races could be paired with the 13th doctor's understanding of current galactic politics. They could work together to save a planet that is on the brink of destruction due to a complex web of time - related issues. The encounter could also lead to some humorous moments, like when they argue about who has the better sonic screwdriver or who has had the more exciting adventures.

The Daleks could be the main villain. They might be trying to manipulate the Doctor's regeneration to create chaos in the time - space continuum. Since the 9th Doctor's unexpected jump to the 11th Doctor disrupts the normal flow, the Daleks could take advantage of this instability to further their evil plans of universal domination.

It could be the Daleks. They are a classic Doctor Who villain. They might see the meeting of two Doctors as a threat to their plans for universal domination and try to stop it.

In fanfiction, when the 13th Doctor meets the 11th Doctor, there could be a lot of chaos and fun. They might exchange stories about their adventures. Maybe they would team up to fight a common enemy that spans across their different timelines.

One of the top 5th Doctor stories could be 'Caves of Androzani'. It's a great story that shows the Doctor's intelligence and courage in a difficult situation. Another might be 'The Visitation' which has an interesting plot with historical elements. 'Kinda' is also a memorable one, exploring complex themes and different cultures.

One possible plot twist could be that they find out they are both parts of a larger plan by an unknown enemy. Maybe an ancient force has been manipulating their timelines to bring them together for some sinister purpose.