The theme of discovery is also very common. Whether it's discovering new things about himself, like his hidden strengths, or about the universe around him. For example, in many fanfics, he stumbles upon something that makes him realize there's more out there than he ever imagined. And also, the theme of friendship. How he forms bonds with others, which later become important relationships in his life.
One common theme is his sense of loss. Since he lost his mother at a young age in most fanfics, it becomes a central part of his character development. Another theme is his dreams of something bigger. Even as a child, he's often depicted as having a longing for a world beyond his small town on Earth.
Another theme is his attempts at romance. Peter is often shown trying to woo Gamora or other characters and failing spectacularly. His clumsy attempts at flirting and showing his feelings end up making him feel embarrassed. In these fanfictions, his big heart and lack of finesse in matters of the heart are highlighted.
Common themes in Peter Quill mpreg fanfiction can be quite diverse. There could be a theme of family, not just in the sense of the new family he is about to have, but also how his existing family (like his mother's legacy or his connection to the Ravagers) plays into this new situation. Additionally, the theme of acceptance, both self - acceptance and acceptance from his friends, is likely to be explored. It could also involve themes of adventure and how this new state of being affects his role in the Guardians' adventures.
One common theme is his origin story. Writers often explore how he ended up as an orphan on Earth and his early days with the Ravagers. For example, many fanfictions might show how he coped with the loss of his mother at a young age.
One common theme is emotional trauma. Peter has been through a lot in his life, like losing his mother and being abducted from Earth. Fanfictions often explore how these past events still haunt him and cause him emotional hurt.
Another theme is friendship or romance. Many fanfics explore the relationship between the female character and Peter Quill. It could start as a friendship based on mutual respect for each other's skills, and then develop into something more romantic as they share more experiences.
Friendship is also a big theme. The OCs form bonds with Peter Quill and the other Guardians of the Galaxy. They learn to trust and rely on each other in the face of various threats. Additionally, redemption can be a theme. Sometimes the OC has a troubled past and through their interactions with Peter and the gang, they strive to make up for their past mistakes.
One common theme is friendship. Given their different backgrounds, seeing them form a bond is always interesting. For example, in many fanfictions, they start off not understanding each other but end up being great friends.
Friendship is also a big theme. He forms bonds with humans, and these relationships are often at the core of the story. These friendships help him to better understand Earth and its inhabitants, and at the same time, the humans he befriends are influenced by his unique perspective and abilities.
There's a fanfic where child Peter Quill discovers an ancient artifact on Earth. In this story, he starts to show his natural curiosity and his penchant for adventure even at a young age. It's really interesting as it also weaves in some of the alien cultures that he would later encounter in a very subtle way.
One common theme is redemption. Yondu had a rough past as a Ravager, and in many fanfictions, his relationship with Peter helps him find redemption. For example, he might change his ways to protect Peter more wholeheartedly.