Maybe Ezra? Although it would be quite a scandalous twist. Given Ezra's complex relationship with the Liars in the original show, his being the father would create a lot of drama and conflict, especially considering his past secrets.
There's also a possibility that it could be a new character introduced in the fanfiction. This new character could be someone who has recently come into Spencer's life, perhaps a mysterious stranger who she has a brief encounter with, and that encounter leads to the pregnancy.
Ezra could be a likely candidate as they have a complex relationship in the original series. It would add more drama to their already tumultuous love story if he were the father.
The father could be Caleb in a really unexpected twist. Imagine how that would change the dynamics between Alison and Hanna. It could also be one of the older guys in Rosewood that we don't know much about, someone who has his own secrets. Maybe it was a drunken mistake at a party. Or, in a more far - fetched but interesting idea, it could be a character from Alison's past that we haven't seen in the show yet, like an old boyfriend from when she was away.
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.
One idea could be Spencer dealing with the shock of the pregnancy while trying to keep it a secret from her friends. She might be worried about how it will affect her academic future and her relationships within the group.
One possible plot could be that Spencer and Marco team up to solve a new mystery in Rosewood. Maybe there's a series of strange events that the police are overlooking, and Spencer's sharp mind combined with Marco's detective skills make them an unbeatable duo.
There are some lesser - known authors who write amazing Toby and Spencer fanfiction. One such author has a unique style where they mix the mystery elements of Pretty Little Liars with the romance of Toby and Spencer. Their stories often have unexpected twists and turns that keep you hooked. They might not be as popular as some big - name authors, but their work is definitely worth checking out if you're a fan of Toby and Spencer.
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.
The parents could also be important characters. Spencer's parents might have concerns about her spending time with a detective, while Marco's family background could be explored. Maybe his parents were also involved in some mystery - solving in their youth, which influenced him.
Well, it's hard to say who the 'best' is as it depends on personal taste. But some popular authors might include those who have a deep understanding of the characters. For example, some authors who have been writing for a long time and have a large following. They are often good at capturing Spencer's intelligence and Toby's more reserved nature.