For Rose's family and friends back on Earth, if they ever find out, it could be a shock. Her mother might be worried about her getting too involved with a time - traveling alien. And for the Doctor's friends among the Time Lords (if there are any left), they might see it as a sign of the Doctor becoming too attached to a human, which could have implications in the grander scheme of the Time Lord society.
The kiss could change how the TARDIS reacts to them. Since the TARDIS has a sort of sentience, it might sense the change in their relationship and act differently. Maybe it becomes more protective of them or takes them to places that are more conducive to their relationship growth. And other characters like Jack Harkness might tease them about it, adding a new dynamic to their group interactions.
The kiss in fanfiction can be a catalyst for change in their relationship. It can bring out different sides of their personalities. For example, the Tenth Doctor might become more vulnerable around Rose after the kiss, showing his softer emotions. Rose, on the other hand, could become more confident in her relationship with the Doctor. This new - found confidence can lead to her taking more initiative in their adventures together, as well as in their relationship.
The kiss can strengthen their relationship immediately. It can break down the barriers of unspoken feelings and make them more open and honest with each other. They might start to rely on each other more in a different way than before, like having a deeper emotional support.
The kiss could also cause some tension within the group. Maybe some characters think Ikuto is not good enough for Amu or vice versa. This could lead to arguments or misunderstandings among the characters. However, it could also bring the group closer together in the long run if they work through these issues. They could learn more about each other's feelings and become more understanding.
For Tomoyo, she might be overjoyed as she has always been supportive of their relationship. She could see this kiss as a sign of their relationship deepening and might start planning more things for them, like new outfits for their future 'dates' in card - capturing adventures.
For Will Turner, if he sees the kiss between Jack and Elizabeth, it would be a huge blow. He loves Elizabeth deeply, and this could lead to a rift between him and Jack. He might see Jack as a traitor, and it would add a lot of tension to their relationship, which was already complex due to their different outlooks on life and love.
Well, for Tyrion, he might see it as a political opportunity. He could try to use their relationship to strengthen Daenerys' claim to the Iron Throne. He would probably start devising plans on how to present their union to the other lords and ladies of Westeros in the best light.
It could make things a bit awkward at first. Some of the Avengers might be surprised, like Captain America who is more traditional in his views on relationships. Others, like Iron Man, might make jokes about it. But overall, it could also strengthen their bond as a team as they see that Hawkeye and Black Widow are more than just colleagues.
If they kiss in fanfiction, it might make Loki jealous. Loki has always had a complex relationship with Thor, and seeing Thor getting closer to Valkyrie could stir up his envy. He might try to create some trouble between them.
The druids would likely be very happy. Freya is one of them, and if she is in love with Merlin, it could mean a stronger connection between Merlin and the druid community. However, some of the more traditional Camelot knights might be skeptical. They are used to a certain order and the idea of Merlin, a sorcerer, being in love with a druid girl might seem a bit strange to them at first.
It could make Sebastian, Ciel's butler, more protective. He might see Elizabeth as a potential weakness for Ciel, or he could also view the relationship as something that could be used to further Ciel's goals. For example, if there are other noble families involved, Sebastian could manipulate the situation based on Ciel and Elizabeth's new - found closeness.