You’ve seen Black Widow as an Avenger and even an Agent of Shield. But on her own time she searches for atonement for her past as a KGB assassin–in ways of which those teams just wouldn’t approve.
Another rec in the ongoing series. Black Widow with amazing art by Phil Noto. So far it’s been loosely linked stories so you can start with any issue. The last few (as of this posting #8 was getting ready to come out) are starting to lean on big names to draw you to the book which makes me a little sad but I do love seeing how she holds her own (and lightly makes fun of) the Winter Soldier and Hawkeye.