There's no official indication in the Marvel canon that Agent Carter would watch Iron Man fanfiction. She comes from an earlier era in the Marvel universe and is focused on her own adventures and the world around her at that time.
Well, if Agent Carter were to read Iron Man fanfiction, it would be an interesting clash of two different eras of the Marvel universe. She might find some of the ideas in the fanfiction fascinating, like the advanced technology Iron Man uses. But at the same time, she would likely be a bit put off by the more outlandish elements. And perhaps she would start to think about how the world has changed from her time to the time when Iron Man exists in the fanfiction, and how different their approaches to heroism are.
Another idea is that Agent Carter is somehow brought to the modern era where Iron Man exists. She could be a bit of a fish out of water, but her old - school skills and no - nonsense attitude could help Tony Stark in a crisis situation. Maybe she has a different perspective on some of the modern technology that he's created and offers some unique solutions.
Some fanfiction platforms might have specific collections dedicated to this crossover. FanFiction.net could also be a good bet. You might have to dig a bit deeper by using the search function and looking for stories that mention both Agent Carter and Iron Man in the summary or tags. Usually, the more popular ones will have a higher rating and more reviews, which can be a good indicator of quality.
I would recommend 'When Agent Carter Met Thor'. It's a unique take on the crossover concept. It explores how Peggy would interact with Thor, a very different kind of character from her own world. It has some great dialogue and action scenes that make it an enjoyable read.
One great 'Avengers Agent Carter Fanfiction' is 'Agent Carter and the Lost Artifact'. It combines the charm of Agent Carter with an exciting adventure plot. It has well - written characters and keeps you on the edge of your seat.
Steve would likely have a complex reaction. Since Peggy was such an important part of his life, seeing her in different scenarios in fanfiction would stir up a lot of emotions. He might be secretly glad that people still remember her and her contributions. Hulk might not care much at first, but if there were action - packed parts in the fanfiction that caught his attention, he could get more involved. And Wanda Maximoff could be empathetic towards Peggy. She might sense the emotions that the writers put into the fanfiction about Peggy and feel a connection, especially if there were themes of love and sacrifice in the stories.
They could be involved in time - travel scenarios. For example, if the fanfiction has a plot where something goes wrong with time, the Avengers could end up in Peggy's era. Steve would be the most obvious connection as he already has a history with her. Another way could be through alternate universe concepts. Maybe in a different universe, the Avengers are formed earlier and they interact with Peggy Carter during her SHIELD days.