One common theme is his struggle for acceptance. Being a young and small character in a world of powerful Transformers, he often has to fight to be taken seriously.
Redemption is also a theme that pops up. Some fanfictions like to explore the idea of Starscream changing his ways, seeking forgiveness or a new path, which can be really interesting as it goes against his traditional 'villain' image.
One common theme is the empowerment of the female character. Since Starscream is typically a male character in the original series, making her female in fanfiction often leads to stories that focus on her strength and ability to break through gender barriers within the Transformers society.
Often, there is a theme of innocence lost. As baby Starscream grows, he may face difficult situations that cause him to lose his initial innocence. Also, discovery is a big theme. Discovering his powers, his place in the world, etc.
Power dynamics is a common theme. Megatron is the powerful leader and Starscream is often vying for power, which creates an interesting relationship in the fanfictions. There's also loyalty and betrayal, as Starscream has a history of trying to overthrow Megatron in the original lore.
One common theme is power and ambition. Since Starscream is always after power, your self - insert character might be drawn into his schemes for power or try to resist his influence. Another theme is loyalty. In the Transformers universe, loyalty to one's faction is crucial. Your character could struggle with loyalty, especially when dealing with Starscream who is known for his duplicity. And there's also the theme of survival. Given the constant battles between the Autobots and Decepticons, your self - insert might be just trying to survive in this dangerous world while interacting with Starscream.
One common theme is the idea of enemies - to - lovers. Given their opposing factions in the show, it's a popular concept to explore how they could overcome their differences. Another theme is redemption. Starscream, being a rather complex and often villainous character, might be on a path of redemption in some fictions, with Arcee playing a part in that.
Friendship is also very prevalent. Bumblebee makes friends with other Autobots or even some unlikely characters. These friendships help him in his adventures and also teach him about loyalty and trust. For instance, he might team up with a small Autobot to face a big challenge together, and through that, their friendship deepens.
One idea could be exploring Starscream's origin as a 'baby' in the context of the Transformers Prime universe. Maybe he was created with a special purpose that was later forgotten or corrupted.
There could be a fanfiction where Baby Starscream is found and adopted by a kind Autobot. In this story, he has to learn to balance his natural Decepticon instincts with the new values taught by his Autobot caretaker. This would be full of interesting character development and moral dilemmas.
You can try looking on fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. They have a large collection of Transformers fanfictions, and there's a good chance you'll find some related to Baby Starscream there.