One of the best Barry Allen stories is 'Flashpoint'. In this story, Barry goes back in time to save his mother, which has a huge impact on the entire DC universe, changing the relationships and nature of many characters.
One of the best is 'The Flash: Rebirth'. It delved deep into Barry Allen's return and his complex relationship with the Speed Force. It also reintroduced many elements of his character and his place in the DC Universe.
Another great one is 'The Trial of The Flash'. This story puts Barry through a lot of moral and ethical challenges as he faces trial for the murder of the Reverse - Flash. It's a story that really tests Barry as a character and shows different aspects of his personality.
One of the highly rated ones might be 'The Flash and the Arrow's Unlikely Bond' on Archive of Our Own. It has a great build - up to their kiss. Another could be 'When Two Worlds Collide' on FanFiction.net which has an interesting take on their relationship leading to the kiss.
Sure. 'Flash: Year One' is a great starting point. It tells the origin story of Barry Allen becoming the Flash in a really engaging way. It has all the elements that make the Flash character interesting, like his scientific background and his discovery of his super - speed.
One great 'Barry Allen and Iris West Fanfic' is 'The Flash's Heart'. It delves deep into their relationship, showing how Barry's speedster abilities sometimes create challenges in their love. Another is 'Iris and Barry: A New Beginning' which focuses on a different take on how they first got together, with a lot of sweet and tender moments. And 'Love in the Fast Lane' is also a popular one, as it combines action scenes from Barry's superhero life with his relationship with Iris.
One great 'Barry Allen and Wally West Fanfic' is 'Speedsters United'. It shows their relationship as they team up to face a new speed - stealing villain. The story does a wonderful job of highlighting their different personalities within the Flash family.