If Jon Snow gets a dragon in fanfiction, he might face new challenges. People would be both in awe and envious of his newfound power. There could be plots against him not just from political rivals in Westeros but also from those who fear the power of dragons. He would have to learn how to control the dragon quickly. Given his noble nature, he might try to use the dragon's power for good, like protecting the smallfolk and rebuilding the war - torn regions.
Perhaps in a fanfiction, Jon Snow gets a castle that has a hidden magic. This magic could be the key to uniting the Seven Kingdoms in a more peaceful way than through war. He discovers ancient secrets within the castle walls that help him in his quest for a better realm.
Daenerys Targaryen is a very likely candidate. Their connection through their Targaryen blood (Jon's true heritage) could be a strong basis for a marriage. They could join their forces, both having a claim to the Iron Throne, and rule Westeros together. Their marriage would also symbolize the unification of the North and the South, as well as the different Targaryen branches.
One implication could be a shift in power dynamics. If Jon Snow has Blackfyre, he becomes a more formidable force, which might make other characters either fear or seek to ally with him.
Yes, there are quite a few. You can start by looking on popular fanfiction websites like Archive of Our Own. Just search for 'Jon Snow married Val' and you'll find a variety of stories, each with their own take on how their relationship could develop into a marriage and what that would mean in the context of the 'Game of Thrones' universe.
Jon Snow could use the castle as a base to improve relations with the other kingdoms. He might hold diplomatic meetings there, inviting lords and ladies from all over Westeros. This would be a big change from his more battle - focused past.
The main characters are obviously Jon Snow and Ygritte. Jon Snow is a member of the Night's Watch who has a complex background. Ygritte is a wildling woman. Their relationship is central to the fanfiction as they are the ones who get married.
One possible plot could be that Jon, after becoming King in the North, realizes that a marriage to Val would be a great way to secure peace with the wildlings. So he marries her, and they face many challenges together as they try to integrate the wildlings into the North's society.
In this fanfiction, the relationship between Jon Snow and other characters would be different. For instance, Sansa might view him as an even greater asset to the North. Theon would likely be in awe of him. His relationship with Arya could also be affected as they might plan new adventures together with the help of the dragon. And his enemies, like Cersei, would be more desperate to get rid of him as his dragon - powered presence would be a huge threat to her rule.
Yes, there are. There are many fanfictions that explore the idea of Jon Snow getting married. Some might pair him with characters from the 'Game of Thrones' universe like Daenerys, Arya (in very different interpretations), or even new original characters created by the fanfiction authors. These stories often take different routes from the original plot and can be really exciting to read.