Often, there might be a theme of support from their friends and the community around them. Since they are in a unique situation, their friends might react in different ways, and that can be a big part of the story. Another theme could be the exploration of their own fears and hopes for the future with a child.
One common theme could be the challenges of impending parenthood. How Solangelo deals with the news, the preparations they need to make, and the changes in their relationship.
Another theme is friendship. In these crossovers, they make new friends or strengthen their existing bond. They might meet characters from other universes and form alliances. It shows how their relationship can develop in different settings.
In 'teachers meet solangelo fanfiction', a frequent theme is growth. Solangelo could be growing as individuals or as a couple with the guidance of the teachers. Also, discovery is a theme. They might discover new things about themselves or their powers through the interaction with the teachers. And sometimes, there's a theme of acceptance, where the teachers come to accept Solangelo for who they are, especially if they are different in some way.
The theme of acceptance also runs through a lot of 'Solangelo first time fanfiction'. They come from different backgrounds - Nico from the underworld and Will from the sun - filled Apollo cabin. Their relationship is about accepting each other's differences, and this is especially highlighted during their first time experiences. Whether it's accepting Nico's powers or Will's more upbeat nature, it's all part of what makes these fanfics so interesting.
One common theme is identity. When they turn into girls, Nico and Will have to reevaluate who they are and how they are perceived. Another theme is relationship dynamics. Their relationship as friends or more than friends may change or be redefined in interesting ways.
One common theme is the exploration of their different personalities. Nico, being a bit more brooding and Will, being more upbeat. Their interactions as they get to know each other better are often explored.
One common theme is survival. Since 'The 100' is set in a harsh world, the pregnancy adds another layer of challenge. The characters have to ensure the survival of the mother and the unborn child in a world full of danger.
Often, the plot involves Will misinterpreting Nico's actions or words as signs that he might be losing him. For example, if Nico is being secretive about something, Will might assume the worst and his jealousy flares up. This then leads to some sort of conflict between them that they have to work through, usually with a lot of emotional conversations and realizations about their relationship.
I'm not sure of specific 'Solangelo pregnant fanfiction' titles offhand. But you can try searching on popular fanfiction platforms like Archive of Our Own. There are often tags and filters you can use to narrow down your search to find the type of Solangelo - related stories you're interested in.
Love and support are common themes. Usually, Bella's relationship with Edward or other important characters deepens as they support her through the pregnancy.
Another theme is the relationship changes. Her relationship with the baby's father might be explored, whether it's a new relationship or an existing one. There could also be changes in her friendships as she focuses more on her upcoming motherhood.