Another way is through a common goal. Let's say they are trying to stop Pan from stealing all the magic in Neverland. As they work towards this goal, they have to make sacrifices for each other. Hook might risk his life to save Emma from one of Pan's traps, and Emma might use her magic in ways she never has before to protect Hook. This mutual selflessness would strengthen their bond and develop their relationship further in the Neverland setting.
Well, they could start by relying on each other's skills. Hook's knowledge of Neverland and his sailing expertise, combined with Emma's magic, would make them a formidable team. As they face danger together, like escaping from a giant sea creature or finding a way through a maze in the jungle, they start to trust each other more, which deepens their relationship.
One plot idea could be that Captain Hook and Emma Swan find themselves in a race against time in Neverland. They have to retrieve a magical artifact before a dark force uses it to destroy all the realms. Along the way, they face challenges from the Lost Boys and some of Hook's old enemies.
The relationship would likely become deeper. Hook would be more protective of Emma, always by her side. Emma might see a new side of Hook, a more tender and responsible side, which would make her fall more in love with him.
Another fan - favorite is 'Our Ever After'. This one delves deep into their relationship, exploring their past traumas and how they overcome them together. It has some really emotional scenes that add a lot of depth to the story. The writing style is also very engaging, making it a must - read for any Captain Swan fan.
Archive of Our Own (AO3) is a great place to start. It has a vast collection of Captain Swan fanfiction, ranging from short one - shots to long, multi - chapter stories. You can easily search for what you're interested in using the tags.
Adventure is also a big theme. They are often on some sort of quest or journey together. For example, they might be searching for a magical artifact while also dealing with their feelings for each other. And there's also the theme of trust. Since they come from different sides, learning to trust each other is a crucial part of many fanfics.
One common theme is redemption. Captain Hook often has a past full of misdeeds, and in these fanfics, his relationship with Emma Swan can be a part of his journey towards redemption. For example, in many stories, he tries to change for her.
In another scenario, both Captain Hook and Emma Swan are held for ransom by a new and powerful villain in their world. They have to work together, using their combined skills and the power of their relationship, to escape from captivity. This could involve Hook using his pirate wiles and Emma using her magic. They might also find unexpected allies along the way who help them in their quest to avoid paying the ransom and defeat the villain.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions, and you're likely to find many about Captain Hook and Emma Swan having a baby there.
Another common trope is the 'Time Travel' trope. Given the magical nature of the 'Once Upon a Time' universe, it's not surprising that many fanfictions use time travel as a plot device. For example, Emma or Hook might travel back in time to change an event that affects their relationship, or they could be sent to the future and have to deal with the consequences of what they see there in relation to their love for each other.
One idea could be exploring the backstories of the lost boys in more detail. Maybe one of them has a hidden connection to a character from the outside world. Another plot could involve a new villain coming to Neverland who has a different kind of magic that challenges Peter Pan. Also, a story about Wendy's granddaughter returning to Neverland to find a lost family heirloom could be interesting.