As a young adult, she formed the violent splinter cell Gene Nation until, under the orders of Morlock leader Callisto, she joined the X-Men to redeem herself.

She made progress controlling her powers and learning a moral code, but eventually fell in with the paramilitary group Weapon X. Sarah Knuckey debuted in Cable #15 (September 1994),[8] created by writer Jeph Loeb and artist David Brewer.

Years later, most of the surviving Morlocks (including Sarah) were apparently killed by Mikhail Rasputin, although they were actually brought to another dimension.

The former Morlock leader Callisto cared for Marrow during this period and displayed a maternal attitude towards the young mutant, although the two are not known to be biologically related.

When she managed to reach the top, Mikhail considered her fit to join his elite fighting team Gene Nation, which eventually became a terrorist group whose mission was to punish humans for their hatred towards mutants.

[volume & issue needed] Marrow also participated in the fight against the returning N'Garai, extra-dimensional monsters who were loose on the grounds of the X-Mansion.

She later traveled to the past with the X-Men, ending up on the Skrull homeworld a short time before the cosmic entity known as Galactus would destroy it.

The suspension-properties of a captured Skrull rescue ship allowed her and her fellow X-Men to make the journey back to Earth in real time, without aging at all.

[volume & issue needed] The change of her features led to major softening of her personality, to the point where she reached out to Jubilee following Wolverine's disappearance in the lead up to "The Twelve" storyline.

With Spider-Man's help (he briefly dated her Sarah personality as Mary Jane was believed dead at this point), she freed herself from SHIELD's control by faking a suicide.

[volume & issue needed] Mike Marts, editor for the X-Men comic books, confirmed in an interview that although Sarah retains some of the physical attributes of her mutation, her actual mutant powers disappeared during Decimation.

[16] She was eventually found by Cable, who provided her with an inhibitor collar built by Doctor Nemesis to suppress her memories and control her powers.

The duplicitous director coerces the Black King into tracking other mutants for his minions to round up in his government sanctioned facilities while under threat of execution.

[23] Even the more socially abrasive amongst Homo Superior are welcomed amongst their growing numbers, as Marrow could be seen amongst an enclave of villainous mutants who accepted his summons.

[26] She also has a healing factor and enhanced immune system, much in the same vein as Wolverine since every time a bone is ripped out a wound which remains closes itself soon after.

Knuckey also jumped off the Brooklyn Bridge twice (something that would have resulted in death or at least crippling injuries) without any major damage, being able to walk away from the scene.

[27] Knuckey is also more agile and stronger than the average woman in her age group and physical condition, and has excellent tracking skills.

Darren Franich of Entertainment Weekly stated Sarah Knuckey embodies "superhero body horror at its finest," saying Swiss artist Hans Ruedi Giger would have appreciated the character.

[28] Deirdre Kaye of Scary Mommy called Sarah Knuckey a "role model" and a "truly heroic" female character.

[30] Sarah Knuckey placed 8th in a popularity contest held by Marvel Comics in 2021,[31] which served to determine who would be the final member of a new X-Men team that would debut during the Hellfire Gala storyline.

She makes a brief appearance in the second issue of the limited series, as a member of the Morlocks, a group of mutants who were victims of Sinister's experiments.