One possible scenario in this fanfic could be that Bucky and Steve notice Tony is overworking. So they start by making sure he eats regularly. Steve might cook his old - fashioned but hearty meals, while Bucky keeps Tony company during meal times to make sure he actually eats. They also likely limit his access to the workshop for a while, to force him to rest. Maybe they set up a little relaxation area in Tony's living quarters with comfortable chairs and soft music.
One common theme is protection. Bucky and Steve often see Tony as someone who needs safeguarding, whether it's from physical threats during missions or from the emotional harm caused by his past. For example, in many fics, they'll stand up for Tony when others in the Avengers question his motives.
One great 'bucky and steve care for tony fanfic' is 'Healing Hearts'. In this fic, Bucky and Steve notice Tony's struggle with post - battle trauma. They start by simply being there for him during his nightmares, bringing him warm milk and sitting with him until he calms down. Their care gradually extends to helping him in the lab, understanding his projects, and protecting him from those who might want to harm him for his tech.
Perhaps they would start by helping Tony with his daily routine. Bucky and Steve are very disciplined, so they might introduce some order into Tony's chaotic life. For example, they could make sure he gets up at a reasonable time, exercises a bit, and doesn't stay up all night in the lab.
At first, it might be a bit rocky. Tony, being used to his own space, might feel smothered by Steve and Bucky's over - protectiveness. But as time goes on, he'll start to see their good intentions. Steve's moral compass will inspire Tony to be a better person, and Bucky's loyalty will make Tony feel secure. Eventually, they'll become like a real family, with Tony looking up to Steve as a father figure and seeing Bucky as a cool older brother.
Friendship and love are also big themes. The relationship between the three can range from deep platonic friendship to romantic love. In some fanfics, they struggle to define their feelings for each other. They support each other through tough times like battles and personal crises, which shows their strong bond.
One great fanfic could be 'The Three Musketeers of the Avengers'. It shows an interesting dynamic between Steve, Tony and Bucky. They start off a bit rocky but then come together to face a common threat. The author does a great job of exploring their individual personalities within the relationship.
I think this kind of fanfic can be quite controversial. In the Avengers universe, Steve and Tony have a complex relationship, and adding such a plot of 'cheating' with Bucky can change the whole dynamic. Some fans might like it for the drama it creates, but others might feel it goes against the original spirit of the characters' relationships.
Friendship is a very common theme. Despite their differences, they come together and form a strong bond. Another theme is redemption. For example, Bucky might be seeking redemption for his past actions, and Tony and Steve play a role in that process.
There's also 'Forging New Bonds'. This fanfic focuses on the post - conflict relationship between the three. It explores how they start to understand and accept each other better. The writing style is quite vivid, making it easy to picture the scenes in your head.