One common theme is loyalty. Gabriel's protectiveness shows his loyalty to Castiel. Another theme is sacrifice. Gabriel might be willing to sacrifice his own well - being or position to keep Castiel safe. For example, he could risk getting on the wrong side of other powerful angels.
I'm not sure of specific fanfiction titles off the top of my head. But you can also try fanfiction.net. Sometimes, fan communities on platforms like Tumblr might also recommend good fanfictions on this topic. You could post a request there, saying you're looking for fanfiction where Gabriel is protective of a hurt Castiel. They might direct you to some great reads.
One possible fanfiction could be that Dean gets seriously injured during a hunt. Castiel, feeling a deep sense of protectiveness, uses his angelic powers to heal Dean as much as he can. He then stays by Dean's side, warding off any potential threats, whether they be other supernatural creatures or even humans with bad intentions. Castiel refuses to leave Dean's side until he's fully recovered, and in the process, their relationship deepens, with Dean realizing just how much Castiel cares for him.
A common theme is the exploration of Castiel's humanity. When he's being protective of the hurt Dean, he starts to understand human emotions like love, fear, and worry on a deeper level. This can lead to his own character development as he becomes more in tune with his human side while still maintaining his angelic essence.
Well, it could be about Gabriel abandoning or departing from a baby Castiel. Maybe it explores the reasons behind his leaving, like some sort of mission or a conflict that forces him to go.
One great 'Castiel and Gabriel fanfic' is 'Heaven's Unlikely Pair'. It beautifully explores their relationship in the context of the Supernatural universe. The story has a great plot that keeps you hooked from start to finish.
Family - like relationships are also prevalent. They are sometimes written as if they were brothers, with Gabriel taking on an older - brother - like role. He might teach baby Castiel about the world, about their angelic nature, and how to use their powers. There could be heartwarming scenes of them bonding over these things.
I remember reading a fanfic called 'Castiel's Wounds'. In this story, Castiel is severely injured during a battle with demons. The fic focuses on how Sam and Dean try to help him recover, and the relationship dynamics between the three are really well - written. It shows Castiel's vulnerability in a very believable way. There's also 'A World of Hurt' which explores Castiel's hurt in a post - apocalyptic setting, adding an extra layer of tension and drama.
One common theme is redemption. When Castiel is hurt, often the story will revolve around him finding a way to redeem himself, whether it's from a mistake he made that led to his pain or just from a sense of lost purpose. For example, in some fanfictions, he might have been hurt because he trusted the wrong entity and then has to make amends.