One possible theme could be a sense of betrayal. For example, if Bilbo feels betrayed by his companions during the adventure, it could lead to his anger. This could be related to issues like sharing of the treasure or decisions made during their journey.
One possible theme could be adventure. Just as Bilbo had grand adventures in Middle - earth, the cat familiar could accompany him, adding an interesting dynamic to the journey.
I'm not sure of a specific 'angry bilbo baggins fanfic' off the top of my head. But you can try looking on fanfic websites like Archive of Our Own. There might be some stories there that explore an angry Bilbo Baggins in various scenarios, such as during his adventures when he's faced with difficult challenges or when he has disputes with other characters in Middle - earth.
Common themes in 'female Bilbo Baggins fanfic' include empowerment. A female Bilbo can be shown as breaking barriers in a world full of challenges. Also, there is often the theme of adaptation. How does she adapt to the quest and the company of dwarves? It's not just about being female, but also about how that changes the story's flow. There might be fics where she has to prove herself more because of her gender, which is an interesting take on the classic story.
One common theme is the aftermath of his adventures. For example, dealing with the trauma of facing the dragon Smaug or the battles in Middle - earth.
A major theme in these fanfictions is the relationship changes. His friends, like the dwarves or Gandalf, might react differently to him as a vampire. Also, the theme of temptation is present. The urge to drink blood and how Bilbo resists or succumbs to it is often explored in detail. For example, in some stories, he has to find alternative ways to satisfy his vampiric thirst without harming the innocent. This adds a layer of complexity to his character and the story as a whole.
Self - discovery is also a theme. Just as Bilbo discovers his own courage and capabilities during his adventures, the OC may also be on a journey of self - discovery. They could be learning about their own powers, their place in the world, or their true identities, all while being influenced by their interactions with Bilbo.
The theme of discovery is also prevalent. Many young Bilbo Baggins fanfictions depict his discovery of new places, cultures, and ideas. This could be his first encounters with elves or dwarves, and how these meetings broadened his horizons and made him question the small - mindedness of some in the Shire.
One common theme is the exploration of gender roles. Since Bilbo is male in the original, making her female in fanfiction allows for a new look at how she would handle situations in a world with traditional gender expectations. For example, how a female Bilbo would be treated by male dwarves during their journey.
Perhaps it's due to his discomfort with sudden changes or surprises. Bilbo is a hobbit, used to the simple and predictable life in the Shire. In fanfics, when he's exposed to the chaos of the outside world, like unexpected magic or the presence of strange creatures, he might flinch as a reaction to this discomfort. This shows his struggle to adapt to new circumstances outside his comfort zone.
The appeal of bamf Bilbo Baggins fanfic lies in the transformation of his character. In the original, Bilbo is a rather meek hobbit at first. But in these fanfics, he becomes this strong, badass character. It's exciting to see him take charge and use his wits and new - found strength in different situations.