Scott would be extremely worried and immediately start planning a rescue mission. He'd be angry at Theo for targeting Stiles and would use his alpha powers to try and track him down. He might also call on the rest of the pack for help, like Lydia, who could use her banshee powers to sense if Stiles was in danger or where he might be.
One possible plot could be that Theo kidnaps Stiles to use him as a bargaining chip with the pack. Maybe Theo wants something from Scott, like the alpha power or a powerful artifact that the pack has in their possession, and he thinks Stiles is the key to getting it.
Well, in Stiles and Theo kiss fanfiction, it often explores a different side of their relationship. Maybe it's a way to show a deeper connection that wasn't fully explored in the original show. It could be a creative way for fans to express their desires for these two characters to have a more intimate bond.
It could also be for power. Perhaps Stiles has some knowledge or ability that Theo wants to use for his own gain. In the show, Stiles was quite smart and resourceful, so Theo might kidnap him to get access to that intelligence or those skills. In some fanfictions, Theo might be trying to use Stiles as a bargaining chip to get something from the other characters like Scott or Derek.
One common theme is friendship. Many fanfictions explore how Theo and Stiles form a strong bond, often starting from a place of mistrust. Another theme is self - discovery. As they interact, they both learn more about themselves.
The theme of inner struggle also frequently appears. Stiles has to deal with his own feelings of anger, pain, and confusion after being hurt by Theo. And Theo may also struggle with his own motives and feelings towards Stiles.
One common theme is the exploration of their relationship, whether it's a slow - burn romance or a more immediate connection. Another theme is often the supernatural elements, as they are usually set in a world with magic or other extraordinary powers.
One great Stiles x Theo fanfiction is 'The Unexpected Bond'. It delves deep into their relationship, starting from their initial animosity and gradually evolving into something more. The character development in it is really well - done.
Archive of Our Own (AO3) is a great place to start. It has a large collection of fanfiction, including many Stiles x Theo ones. You can search by tags and ratings to find the ones that suit your taste.