Natasha became the new assistant for Tony Stark, who, on the day she arrived, told her to go into the boxing ring while he'd Googled her finding out that she could speak French, Russian and Latin. While she was still in the ring, Happy Hogan teased about punching her but she tackled him to the ground. She then assisted Tony while he was in Monaco. She attended Tony's birthday party and flirted with him and he started to get suspicious about where she had come from.
She appeared with Nick Fury when he talked to him in Randy's Donuts, Tony was shocked when he saw her in a S.H.I.E.L.D. uniform, Fury revealed her true name and she gave Tony a serum. Natasha along with Fury and Phil Coulson
went to Tony's house and she was told by Fury that she will stay acting
as an assistant. Even after Tony learned that Romanoff was a
S.H.I.E.L.D. agent, she stayed on as his assistant more to keep a eye on
him than anything.
Natasha was attending the Stark Expo show, when Ivan Vanko took control of Hammer's Drones. Natasha ran out and found Happy Hogan and told him to drive the car to get her to Hammer Industries. After changing into a S.H.I.E.L.D. uniform during the drive, she broke into Hammer Industries to stop the drones. She encountered and took out several security men. Using technology at Hammer Industries, she managed to get control over War Machine's suit.