It was a shitty thing to lie about, there was no ambiguity on that front, but Natasha had never been overly concerned about doing something shitty if it was in the name of survival - a characteristic she quite obviously shared with every single other victor except Steve, and it wasn't as though she was worried about opinions. It would work, and the more important aspect that Tony had latched onto was that it would be simple, it wouldn't complicate or compromise any other aspects of the rescue plan. There was something reassuring about Tony's reaction, in a strange way, or maybe just an affirmation; in spite of everything else, she hadn't lost her talent for this, for finding the straightest path through a problem.
Children were never something she'd thought about, not in a way other than 'how to take strident measures to prevent even the possibility'. Natasha had never been interested in them, had never quite left the phase of her life where 'a baby' didn't seem like anything other than the worst possible outcome of sex. Then again, she had never really understood how anyone left that phase, in the world they lived in. Still, she imagined it wouldn't be too hard sell it, at least enough to get past Steve's not-all-that-keen sense of detection, and it wasn't as though she'd have to do it for long enough that they'd need to start investigating foam belly options.
"I think you're right," she said, turning the options over. "Bucky's child might be the stronger pull for Steve, but there's too much margin for error on that one - Steve's a leaky sieve, all Bucky has to do is tell him we've never slept together for them to know something's up. It'll have to be Clint. And if you're afraid he won't be able to properly lie to Steve, I suppose we don't have to tell Clint it's a lie. The timing of it would still check out." Her mouth pulled a little to the side; she was a little less in love with that idea for a few reasons. One of which was that if Clint truly thought he'd gotten her pregnant, he would get reckless in the name of protecting her once they were inside the arena, and none of them could really afford that.
The second of which was that he would likely be genuinely thrilled at the possibility, particularly if escape to Thirteen and someplace where a victor's kid could be raised without the shadow of the Games hanging over its head was on the table. There would be hope in him, and Natasha didn't want to be the one responsible for devastating him if they made it to the other side and she had to tell him it had never been true.
"Besides, there's a chance Clint's already told Steve that I agreed to marry him," she added. "They haven't exactly been on speaking terms, but you know Clint can never really hold a grudge to save his life. There's never been much anger in him." He was an intrinsic peacemaker, who wanted to be liked by people and liked plenty of them in return, and eventually, that was the part of him that always rose to the surface. "And it's the sort of news he would probably want to share. I haven't had a chance to check in with him and see. So...there are a few ways to play it, I think, as regards looping him in or not. Advantages and disadvantages to both."