I'm not entirely sure specifically what this fanfiction is about without reading it. But generally, in the context of a Bucky fanfiction, it could explore different aspects of his life. It might be set in the Marvel universe and involve other characters like Steve Rogers or the Avengers. It could be a story of love, friendship, or even a mission that Bucky undertakes that is so exciting that you'd stay up all night to finish reading it.
You can try searching for it on popular fanfiction websites such as Archive of Our Own (AO3). AO3 has a vast collection of fanfictions from various fandoms, and there's a good chance you'll find the 'up all night to get bucky' fanfiction there.
Well, in this kind of fanfiction, it might show Bucky's loyalty to Tony. Maybe Tony is in some sort of trouble, and Bucky decides to support him. It could be related to the complex relationships within the Marvel universe. Bucky, with his own set of values and experiences, steps in for Tony, which can lead to interesting character developments and interactions.
It could also be strained. There might be some jealousy or differences in opinion on how to handle the situation. For example, one of them might want to be more involved with the girl during the pregnancy while the other feels left out, which could cause some tension between them.
No. Fanfiction that involves sexual content is not suitable for all audiences, especially younger viewers or those who are not interested in adult - themed stories.
One possible theme is friendship. Despite any past issues, Bucky choosing to stand up for Tony shows a form of friendship. Another theme could be redemption. Bucky might be trying to make up for past wrongs or misdeeds by helping Tony.
In the fanfiction, it could be that there was some sort of mission or adventure that brought the three together. During that time, the relationship developed and the girl got pregnant. Steve and Bucky might then use their skills and resources to protect the girl and prepare for the baby. They could have to deal with enemies who might want to harm the girl because of the baby or their relationship.
In the comics, Bucky and Natasha don't get married. Their storylines focus more on their individual adventures and interactions with other characters rather than a romantic commitment to each other.