In order to use the Staff of One more effectively, she has learnt the same word in multiple languages. Introduced in Runaways #1 (2003) by Brian K. Vaughan and Adrian Alphona, Nico and her parents were one of six families that would hold an annual “charity event” at one of their mansions. One year, the kids decided to spy on their parents and the kids witnessed the parents murder an innocent girl, discovering that they were supervillains called the “Pride”. Fleeing the house, the six teenagers vowed to stop the Pride and became known as the Runaways, with Nico taking the name Sister Grimm. Nico re-encountered her parents again and learnt that they were Dark Wizards and they attempted to jam the Staff of One into her chest, but her body absorbed it. After a while, when team leader Alex was revealed to be a mole, the team defeated the Pride and Nico became team leader.

Nico would be sent to a new school where she would battle Marie Laveau, a former rival of her parents. Using Laveau’s Black Mirror, she tried to revive Alex but failed. She would return to the Runaways. After finding Victor Mancha, they helped the “son” of Ultron against his father and invited him to join the team. Karolina Dean, another member of the Runaways kissed Nico, but Nico rejected her, unsure of her sexuality at the time. After stopping Chase from sacrificed himself to the Gibborims, Iron Man and the SHIELD found the team, which led to the team running across the country to escape.

The team would be sent back in time, where Nico would be kidnapped and trained by her ancestor. They would help civilians during the Secret Invasion, which saw them teaming up with the Young Avengers. After the team broke up and reunited a couple of times, Nico and Chase were kidnapped by Arcade and force to take part in the Avenger Arena event, which saw Nico lose her arm. She would later help the survivors track down Arcade and those involved to seek revenge. After Secret Wars, she would join the A-force and somehow regained her arm. She would rejoin the Runaways and started a proper relationship with Karolina. The pair would join the J-Team with Nico also taking up a teaching role at Strange’s Academy.

Out of all the Runaways, Nico has been the character to appear the most outside the team, gaining quite a following. She would receive a figure as part of the Dr. Strange Dormammu wave.