The key elements often include a new plotline. Since Dean is an addition to the PLL world, the fanfiction usually creates a new story around him and Spencer. It could be a romantic plot, like a slow - burn relationship between them. Or it could be a friendship - based plot where they support each other through the chaos of Rosewood. Also, the adaptation of Dean's character to fit the PLL style is important. His backstory might be tweaked to match the overall tone of the show.
One key element is the character interaction. How Spencer, with her intelligence and complex personality, interacts with Dean, who likely has his own set of skills and traits. Another is the setting integration. Incorporating the dark and mysterious world of Pretty Little Liars with Dean's possible role in it. Maybe he could be helping to uncover the 'A' mystery or dealing with the other secrets in Rosewood.
A possible plotline is that Dean has a connection to one of the 'A' characters from his past that he doesn't remember at first. Spencer helps him dig into his past and they find out that his family has some sort of history with the chaos in Rosewood, which puts both of them in danger but also brings them closer together.
Aria could also be a good addition. Given her creative and artsy side, she might offer different insights compared to Spencer and Dean. She could also be involved in a love triangle situation, which would add more drama to the fanfiction. For example, if both Dean and Ezra were interested in Aria at the same time while she was friends with Spencer and Dean.
Character development is crucial. You need to understand Spencer's intelligence and her insecurities, and Andrew's own personality traits. For example, if Andrew is portrayed as a bit of an outsider, it can add depth to their relationship as Spencer, who is part of the main group, bridges that gap.
Sure. One great fanfiction is 'Spencer and Dean's Unlikely Alliance'. It delves into a scenario where Spencer meets Dean under mysterious circumstances and they end up working together to solve a mystery in Rosewood. Another one is 'Dean in Rosewood' which has an interesting take on how Dean would fit into the Pretty Little Liars world and his interactions with Spencer.
One common theme is forbidden love. Since there are so many secrets and complications in the show, this often translates into their relationship in fanfiction. Another theme is mystery, as both characters have their own secrets, and fanfic writers like to explore how these secrets affect their relationship.
One common theme is mystery. Since the show itself is full of mystery, fanfictions often continue this trend. Spencer and Alex might be involved in solving a new mystery together, perhaps related to their families or the town's secrets.
Another reason is that they both have had their own share of troubles in the show. By pairing them in fanfiction, it gives the writers a chance to show how they can heal each other. Spencer, with her family problems, and Caleb, with his past in foster care, can find solace and love in each other. This aspect of two damaged souls coming together is very appealing to many fans who write and read fanfiction about them.
In fanfiction, Wren and Spencer often have a complex relationship. Sometimes, they are depicted as having a secret, passionate affair. Wren's mysterious nature adds an element of intrigue to their connection, while Spencer's intelligence makes their interactions intellectually stimulating.
I'm not sure who the 'best' is as it's subjective, but some popular authors might be those who have a large following on fanfiction platforms. Look for ones with high ratings and lots of reviews. For example, there could be an author named 'RoseWriter' who is known for her detailed characterizations of Emily and Spencer.
There are many great writers out there. Some popular ones are often those who are really good at capturing the personalities of Spencer and Toby as they were in the show. For example, some writers on fanfiction.net have a large following for their PLL fanfics. But it's really subjective, as different people like different writing styles.