Another storyline could be about their growing feelings for each other in the backdrop of the chaos of Age of Ultron. Maybe Natasha is injured during a battle, and Steve is forced to confront his true feelings as he takes care of her. This could lead to some tender moments between them and a deeper exploration of their connection.
Their relationship could develop through shared experiences. For example, fighting side by side against Ultron's forces would build trust. Steve might admire Natasha's skills and her ability to adapt, while Natasha could be drawn to Steve's unwavering sense of justice.
Steve's straightforwardness and Natasha's secrecy can be both a point of clash and complement. Steve may not always understand Natasha's need to keep things hidden, which can lead to arguments. But in a mission, Natasha's ability to keep secrets can be an asset, and Steve's honesty can be a refreshing change for her. They balance each other out in many ways, like two sides of a coin. Steve's idealism gives Natasha hope, and Natasha's realism keeps Steve grounded in the real - world implications of their actions.
It could start slowly. Maybe they first notice each other during a lecture at Avengers University. Steve is intrigued by Natasha's quiet confidence, and Natasha is curious about Steve's old - fashioned values. They gradually become friends as they study together in the library. As time passes, they find themselves thinking about each other more and more, and eventually, their friendship turns into a romantic relationship.
The chemistry between them in the movies is palpable, though not fully explored romantically. Fanfiction writers see this potential and want to expand on it. They can create different scenarios, like what if they had more time together during certain events in the MCU timeline? This gives a lot of room for creativity.
One plot idea could be Natasha and Steve having to go undercover together during a mission related to Ultron's early schemes. They could pretend to be a couple, which would lead to some awkward yet heartwarming moments as they navigate their feelings while also trying to stop Ultron. Another idea is that Natasha discovers a hidden past of Steve that is somehow connected to the creation of Ultron and they have to deal with the revelations together.
Fanfiction.net is also a good place to look. It has a large collection of fanfictions. Navigate to the Marvel section and then start looking for stories with the specific tags or keywords related to Steve, Natasha, and Bucky. However, the search function there might not be as advanced as AO3, so you might need to do a bit more digging.
One great 'Natasha Romanoff x Steve Rogers fanfiction' is 'Red and Blue'. It beautifully explores their relationship dynamics against the backdrop of the Avengers' missions. The story delves into their shared experiences, like how they both have a sense of loyalty to a cause that goes beyond themselves. Their mutual respect and the underlying tension between them are well - captured in this fic.
Another great one is 'Unlikely Allies'. It delves into how Steve and Natasha, who are very different in many ways, find common ground and eventually fall in love. It shows their journey from just being teammates to something more, with detailed descriptions of their interactions and internal thoughts.
The relationship can develop through their shared anticipation of the baby. Steve can become more in tune with Natasha's emotions, and they can have deeper conversations about their future as a family. For example, they might talk about how they'll raise the child, whether they want a traditional or more unconventional upbringing.