[Bucky/Sharon]
I know Natasha Romanova pretty well. Or I did, anyway. She's clever, competent, trustworthy, always thinking six moves ahead. You don't always know what she's up to or what her game is, but you can still trust and believe that she's on the right track. That she's got a good reason for whatever she's doing. That she's probably got a better handle on the situation than you do.
My experience with her counterpart hasn't given me a lick of insight into who Natasha Romanoff is, or what the fuck she's up to.