It’s really Brubaker’s pairing, anon! I don’t put his whole Captain America run on my recs list because it’s a Captain America run, basically, about Captain America and not Black Widow. But it’s good comics. In recent years it has become a confusingly-numbered beast:
- Captain America v5 #1-24
- Winter Soldier: Winter Kills #1
- Captain America v5 #25-50
- Captain America #600
- Captain America: Reborn #1-6
- Captain America: Who Will Wield the Shield? #1
- Captain America #601-619
- Fear Itself #7.1
- Captain America and Bucky #620-624
- Winter Soldier #1-current
Natasha doesn’t show up until issue #27, and you can definitely start reading from issue #25— but I do think it’s worth it to read the whole thing from the beginning. From #27 on she’s a pretty strong presence.
There’s also the Roger Stern and Sean McKeever stuff that ties into the Brubaker Captain America run: Young Allies 70th Anniversary Special #1, Captain America: Forever Allies #1-4, and Nomad: Girl Without a World #1-4.
From the more Natasha-centric side of things, Black Widow v6 #1-5: “The Name of the Rose” is very good, a must-read for anyone following this blog! Black Widow: Deadly Origin #1-4 and Secret Avengers #15 also touch quite a bit on her relationship with Bucky, but they aren’t as good, imho.