You can try Archive of Our Own (AO3). It has a large collection of fanfictions, and you can easily search for Barry Allen and Peter Parker related ones. Just type in their names in the search bar and you'll get a list of relevant stories.
You can try searching on popular fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. Just type in 'Peter Parker x Liz Allen married' in the search bar, and it should show you relevant stories if there are any.
There are fanfictions where Barry Allen visits Peter Parker's universe. For example, Barry could be accidentally sent to Peter's world while trying to fix a problem in his own timeline. There, he meets Peter and they end up sharing their superhero experiences and helping each other with their personal problems like Peter dealing with his school and love life, and Barry with his family issues.
As I mentioned before, Archive of Our Own (AO3) and Fanfiction.net are good places to start. Just use their search functions and type in relevant keywords like 'Peter Parker', 'Liz Allen', and 'pregnant' to see if any relevant stories pop up.
Archive of Our Own (AO3) is also a great place to look. It has a very inclusive tagging system. So, you can easily find Barry Allen harem fanfiction by looking through the relevant tags. There are often detailed descriptions and reviews to help you choose the stories you might like.
You can start by looking on fanfiction.net. It has a large collection of fan - made stories, including many about Barry Allen and his potential harem. Another good place is Archive of Our Own (AO3). It has a wide variety of fanfictions, and you're likely to find some interesting Barry Allen harem stories there as well.
You can try websites like Archive of Our Own (AO3). It has a large collection of fanfictions, and you can easily search for 'Dark Barry Allen' within its search bar. There are likely many different interpretations of a dark Barry Allen there.
Some fandom - specific forums or communities might also be a great source. There are often members who share their own fanfictions or recommend good ones they've read. For example, there could be Marvel - related forums where fans discuss and share these types of crossover fanfictions.
Some dedicated superhero fanfiction forums might also have Barry Allen and Kara Danvers stories. These forums often have a community of fans who write and share their own fanfics. You might need to register on the forum to access all the content, but it can be worth it as you can interact with other fans and even request for specific types of fanfictions.
Fanfiction.net is also a great place to look for Barry Allen x Reader fanfiction. However, it might be a bit more difficult to specifically find 'lemon' content as their rules are a bit stricter regarding mature themes. But you can still find a good number of general Barry Allen x Reader fics to enjoy.
You can start by looking on fanfiction websites such as Archive of Our Own (AO3). It has a large collection of fanfiction, and you can use the search function to specifically look for Peter Parker - related stories. There are also some dedicated Spider - Man fanfiction forums where fans share their works. Another option is to check out Wattpad, though the quality can vary more there. Just make sure to read the tags and descriptions carefully to find the ones that suit your taste.