okay i see it. considering they're in the same universe and dani canonically worked for SHIELD, i think they could've met. personally i think dani has such a take-no-shit personality and nat is more like sit-down-and-take-it-but-get-revenge-later type.
if they ever had sex i think dani would use her powers to enact her own "greatest desire" (probably after some goading from nat), and their sex would be a lot of degredation, specifically from natasha, and it would become like a competition as both of them tried to top.
i personally don't think it would happen, i feel like they're such different character, especially with dani having a steadfast moral compass and nat, well also having that but also yknow. the murder-y assassin thing. i mean i could see it but i also couldn't yknow? if that makes sense. a bit of a "opposites attract" vibe but also like an rivals/competition thing. especially since she's also an archer like clint and i know nat and clint have a very will-they-won't-they-someone-please-stop-them dynamic. so