Well, 'Pride and Prejudice' can be considered in a way. Darcy and Bingley have a great friendship which is a form of bromance. Bingley is more easy - going and Darcy is more reserved, but they support each other. Another one is 'To Kill a Mockingbird'. Jem and Dill have a fun and supportive relationship that can be seen as a bromance. They get into adventures together and are there for each other.
Harry Potter, Ron Weasley, and Hermione Granger also have a kind of bromance (although Hermione is a girl, their friendship has a strong bromantic element). Harry and Ron's relationship is especially bromantic. They are best friends from the start at Hogwarts. They face numerous challenges together, from battling dark wizards to getting through school exams. Their friendship is full of loyalty, humor, and mutual support.
One of the best bromance stories is that of Frodo and Sam from 'The Lord of the Rings'. Sam was always there for Frodo, through all the hardships in their journey to destroy the One Ring. He carried Frodo when he couldn't walk, and his loyalty was unwavering.
Mutual respect is essential. In the bromance between Captain Kirk and Mr. Spock in 'Star Trek', they respect each other's different strengths. Kirk is more impulsive and action - oriented, while Spock is logical and calm. They value each other's input and work together to explore the galaxy. This mutual respect allows their relationship to thrive and be considered one of the best bromances in science - fiction.
I highly recommend 'The Hobbit'. Bilbo Baggins and Thorin Oakenshield have a wonderful bromance. They start off with some differences but as their journey progresses, they develop a deep respect and friendship for each other. It's a story of two very different characters coming together. Also, 'The Adventures of Huckleberry Finn' where Huck and Jim's relationship has elements of bromance. Huck grows and learns from his time with Jim.
A really cool moment is when they prank the other campers together. Leo uses his inventions to create some wild contraptions, and Percy uses his water powers to set up the perfect scenario. It shows their fun - loving side and how well they work together as friends.
There's also 'Bromance on the Argo II'. This fanfic is set on the Argo II and shows the different bromances among the characters. Percy's interactions with Leo and Frank are really interesting. It shows how they joke around, have each other's backs during battles, and how their friendships evolve into something deeper, which is really a great read for fans of bromance in the Percy Jackson universe.
Trust is a key element. In a great bromance like that of Butch Cassidy and the Sundance Kid, they trusted each other completely. They knew that in any dangerous situation, the other would be there for them. This trust allowed them to face all kinds of challenges together.
One great undercover bromance romance novel is 'Red, White & Royal Blue'. It has elements of friendship that gradually turn into a deeper romantic connection while there are also elements of being 'undercover' in a sense, as the two main characters have to navigate their relationship within the context of public life and expectations.
Definitely check out 'The Outsiders' by S.E. Hinton. It has a strong bromance element among the boys in the gang. They rely on each other, protect one another, and share a unique bond that is tested throughout the story. The story shows how these boys, from different backgrounds but united in their friendship, face the challenges of their world.