Warning: spoilers ahead for Black Widow #4!
Loving Marvel Comics often means being asked to accept unlikely things. Sometimes it's the Black Panther dying in a simple fall, sometimes it's Spider-Man having a long-lost super-spy sister, and sometimes it's that a man with a bow and a woman with some spy training can keep up with Iron Man, Thor, and the Hulk on their most dangerous missions, and even get the chance to save the day every now and again.
But for true fans of Marvel, it feels natural that Black Widow has a place on the roster of Earth's Mightiest Heroes. An expert assassin and one of the most effective secret operatives in the world, Natasha often perseveres where more directly powerful heroes have fallen, leading the fight back in Marvel's Secret Invasion event and working undercover to stop Norman Osborn during his Dark Reign. However, recent storylines have put Natasha through the ringer, with her experiences and abilities turning her into an even more ferocious warrior with a lot in common with the X-Men's Wolverine.
From the start, Black Widow was a deadly killer on par with Wolverine (he even helped train her as a child), becoming the only hero the super-villain Taskmaster truly fears. Sadly, she and Logan also share a history of repeated brainwashing, with Black Widow originally having her memories of her youthful Red Room training replaced with a history as a ballet dancer, later having her memories altered in Winter Soldier by Ed Brubaker and Butch Guice, and then having an entire false life implanted in her mind in Kelly Thompson and Elena Casagrande's ongoing Black Widow. Like Wolverine, Black Widow is an artificially long-lived hero - having been given a substance similar to the Super-Soldier Serum - who has been brainwashed again and again to make her a killing machine, but the links go far deeper.
The big change that has made Natasha so similar to Logan is her recent death and resurrection. While the Black Widow doesn't have Wolverine's healing factor, 2017's Tales of Suspense by Matthew Rosenberg and Travel Foreman revealed the Red Room had a policy of cloning Natasha on her death. While one clone received her actual memories and destroyed the cloning facility - becoming the new Natasha - her recent series has made it clear that her enemies noticed the resurrection, which, combined with her prior skill, has made them think she's literally unkillable, just like Wolverine.
It's unclear if this storyline will influence the MCU, where the Black Widow as played by Scarlett Johansson is currently dead despite her upcoming movie - but in the comics, Natasha has "survived" so many deadly attacks that her enemies have given up on the idea of killing her, instead trying to trap her in a Total Recall-style false life. This cloning twist doesn't quite give Natasha Wolverine's healing factor, but with a pile of false memories, the reflexes of a killer, and the ability to return from deadly injuries (albeit before she blew up the one facility she knew about), Black Widow is no longer the powerless spy on the Avengers' roster, but rather a deadly clone with an extended lifespan and a disdain for staying dead.
Sadly, Black Widow's beefed-up abilities come with the same drawbacks as Wolverine, and Black Widow #4 saw her family assassinated by the villains who had sought to keep her under control - a fate Logan has suffered many times. As the story continues, it's likely the Black Widow will unleash bloody, Wolverine-style vengeance on her enemies. Hopefully, unlike the razor-clawed X-Man, she can also eventually find some peace.