Yes, there are some out there. Some fanfictions might explore unique relationships within the Avengers universe with the concept of Spiderman being mpreg. However, this is a very niche and often not part of the mainstream canon. It can be a creative way for fans to explore different character dynamics and storylines.
One common theme could be the struggle of Spiderman dealing with the unexpected situation. Another might be the support or lack of it from the other Avengers.
The three Avengers could be Iron Man, Captain America and Thor. Iron Man could provide the high - tech gadgets and strategic thinking. Captain America would bring leadership and his combat skills. Thor with his godly powers like lightning and super strength would be a great addition. They would each have different interactions with Spiderman, for example, Iron Man might be like a mentor to him, while Thor could be more of a friendly rival in terms of strength.
One great 'Avengers and Spider - Man fanfiction' is 'The Friendly Neighborhood Avenger'. It combines Spider - Man's street - level heroics with the grandeur of the Avengers. It has an interesting plot where Spider - Man has to teach the Avengers some of his unique ways of dealing with small - scale threats while also learning from them about handling large - scale disasters.
There's also 'Spiderman's Avengers Adventure'. This fanfic delves into what would happen if Spiderman had to lead the Avengers in a crisis situation. It's full of character development, especially for Spiderman as he steps up to the plate. The story has a great balance between his quippy nature and the seriousness of the situation.
It depends on the type of fanfiction. In some darker or more angst - filled fanfictions, it is quite common as it adds drama. However, in more positive or team - building - focused fanfictions, it's not as common. These types of stories usually focus on the Avengers and Spiderman working together and getting along. So, it varies from one type of fanfic to another.
Spiderman might use his agility and web - shooting abilities. He could quickly web up Venom, restraining his movements and preventing him from attacking the Avengers.
One common theme could be the exploration of new relationships. For example, how Spider - Man's relationships with other characters change when he is in a situation of male pregnancy. Another theme might be the struggle with his superhero identity. He has to balance being a superhero and dealing with the physical and emotional changes of pregnancy. Also, the theme of support from his friends and family (or lack thereof) could be explored.
The other Avengers would be devastated. Iron Man, for instance, might feel guilty as if he could have done something more to protect Spiderman. He might become more withdrawn and focus even more on creating better technology to prevent such tragedies in the future.