This post just made me wonder if I actually have any head canon for this particular pairing or the MCU in general. I can’t really think of much except maybe our two favourite assassins patching each other up after a mission, but I guess that’s fanon rather than my personal head canon. It’s weird, because I have other ships where I have a very elaborate back story that’s completely made up of fanon and head canon. With some of those I sometimes even have a hard time remembering what’s actual canon and what’s not.
However, the MCU is the one fandom where I multiship and am generally open to various kinds of storylines and AUs (or at least a lot more than in other fandoms). Maybe that’s the reason why I don’t have any real head canon.

Although, come to think of it, Natasha babysitting the Barton kids, while Clint and Laura are out on a date probably counts. She’s trying her best not to appear too thrilled every time Clint asks her to babysit, although she secretly loves spending time with the kids, because it allows her to be a kid herself. After all, she’s never had an actual childhood.