When Clint is tasked to take out the Black Widow he doesn't think much about it.
She is a dangerous assassin with bloods of innocent people on her hand.
He tracks her for two weeks, and then one day sees something that rocks him core.
Widow is helping a little girl who scraped her knee.
She doesn't leave until the mother comes.
He knows Widow isn't just an assassin when the little girl kisses her cheek.
The Widow is crying.
Maybe she is not beyond redemption after all.
He spares her.
Gives her a chance to redeem herself.
Years later as he holds his pregnant wife in his arms he knows he made the right call.