Every year, Nico's parents joined five other couples in a "charity event." One year, Nico and the other kids decided to spy on their parents.[1] Nico was shocked to discover her father speaking an enchantment, and after witnessing the murder of an innocent girl by their parents ("The Pride"), Nico joined the others in their massive ransack to run away from their parents.[2]
While on the run, Nico encountered her parents. Her mother, wielding a large staff with a ball at the end ("the Staff of One"), revealed that she and Nico's father were dark wizards. She then attempts to jam the Staff into Nico's chest. Nico's body, curiously, absorbed it. After she was later cut by Dale Yorkes' Samurai battle-axe, the Staff re-emerged from her chest, which prompts Nico to use the phrase "Freeze", and froze Stacey Yorkes. Nico was discovered to be a witch, and the Staff would only emerge when she bled.[3] Sometime after running off, Nico took on the name Sister Grimm to escape the name her parents gave her, but dropped it after a while.[4] After team leader Alex outed himself as a mole and was defeated along with the Pride, Nico was accepted as the groups' leader.[5]
Following the team's initial dissolution, Nico was sent to live at Father Flanagan's Home for Unwanted Goth Kids.[6] While there, she was soon talked into going to a nightclub with her friends, where she met her parents' old rival Marie Laveau; Laveau sought revenge on Nico's parents for stealing the Black Mirror, one of the four Cornerstones of Creation. After Laveau explained that she needed Nico's blood to activate the Black Mirror, Nico willingly offered it up, knowing that this would bring out the Staff of One. The two fought, and Nico easily prevailed. Having regained the mirror, Nico attempted to bring back Alex Wilder using the Mirror, however the spell failed, the Mirror shattered and the last page of the Darkhold was revealed behind the glass. Laveau took it and fled, while Nico accepted her place as an outcast and with the Runaways.
As a fugitive
After being warned of a future threat named Victor Mancha, Nico and the Runaways found and abducted Victor to question him. After Victor's mother was murdered and Ultron, his father, was destroyed, Nico invited Victor to become a part of the team, much to the anger of some members, notably Chase. Nico reassured them that she was willing to "rip Victor's damn heart out" if necessary.[7]Karolina tried to kiss Nico, revealing that she was a lesbian.[8]
After Chase tied Nico up before he attempted to sacrifice himself to the Gibborim, Nico interpreted it as a cry for help and led the Runaways to intervene Chase's self-sacrifice. The Gibborim instead attempted to take Nico, revealing that Nico's soul was innocent, thus, suitable for the Gibborim's consumption. Victor rescued Nico and the two formed a relationship. After defeating the Gibborim, Victor asked Nico what she was willing to do if Chase did something like this again; Nico responded by saying she was willing to "rip Chase's damn heart out" if necessary. After returning to their lair beneath the La Brea Tar Pits, Xavin realized she had publicly exposed their location, drawing the attention of Iron Man and S.H.I.E.L.D.. Nico, stepping into her role as a leader, led the Runaways in a cross-country escape from Iron Man and S.H.I.E.L.D.[9]
The Witchbreaker
After escaping the authorities, the Runaways headed to New York where Nico anxiously made a deal with the Kingpin.[9] In a twisted turn of events, the Runaways ended up time-displaced in 1907 New York, where Nico was kidnapped and brought to a woman named "the Witchbreaker." The Witchbreaker claimed she was Nico's great-grandmother, and stated she would teach Nico how to withstand more pain and, therefore, wield more magic with better proficiency. She wielded a weapon similar to the Staff of One, with more adornments. When reunited with her comrades, a significant development to Nico's abilities was evident, where she was freely able to float, displayed more proficiency and confidence in casting spells and was able to use a spell with an effect more complicated than most of her others thus far. Somehow Nico had obtained the Witchbreaker's Staff. During this period, Victor fell in love with another girl, corrupting his relationship with Nico.
Secret Invasion
During the global shape-shifting alien invasion by the Skrulls, Nico and the other Runaways briefly remained in New York after returning from 1907, trusting that "hiding in plain sight" would be sufficient to conceal their own identities and that it would be best if they showed Klara around her city in the future before they returned to Los Angeles. However, to their shock, an armada of Skrull ships attack New York and its civilians. Xavin, trying to fool the invaders into thinking she intended to help them, used a force field to knock out the Runaways; Nico and Victor were still conscious, however, and they attacked Xavin, accusing her of being a traitor. Xavin revealed that she was trying to protect them and convinced them that the Skrulls were too dangerous for them to fight and pled with them to flee to the Leapfrog. The Runaways eventually united with the Young Avengers to assist against the invading Skrulls. Nico insisted on leading her team to help the Young Avengers continue the fight against the Skrulls, refusing to "run away." However, Wiccan urged her to leave, claiming that if the Young Avengers lost, they would need the Runaways to save them.
Dead Wrong
Nico used a spell ("scatter") to scatter a group of invading Majesdanians all over the planet. The spell, however, had unwanted side-effects: it emotionally scattered the Runaways.[10] Victor realized this in time, and Nico spearheaded a massive escape from the returning Majesdanians. A short time later, the Runaways realized that having obeyed Nico, they broke the enchantment. Regardless, Xavin shapeshifted into Karolina and left Earth, much to the other Runaways' great grief.
Later on, Nico used the spell "Zombie Not" to turn an army of zombies back to humans. The spell backfired, actually turning the zombies into a "zombie knot", thus creating a one large zombie. The Runaways deduced that after the Witchbreaker tortured and trained Nico, Nico's magical abilities had been severely augmented.[11] Val Rhymin's magician informed Nico that the Staff of One carried tremendous magical ability and Nico, being young, should not use it. The magician stole the Staff from her, only to be killed after the Staff defended itself. A silent Nico took her Staff back, and warned the other Runaways not to touch it.
Home Schooling
Nico dedicated her efforts to providing normalcy for her teammates. She tried to enroll Molly in the Xavier School's San Francisco campus, but this backfired when one of the many victims of Molly's late parents kidnapped her. Later, she tried to stage a prom in an attempt to give her older teammates an outlet for their sexual tension, which had been growing worse after Victor lost Lilly and Karolina lost Xavin. This also backfired, as Victor, who'd been given the task of finding music, hacked into what he thought was some shut-in's private radio station. The radio signal was actually coming from a naval air weapons base that was awaiting the arrival of a mysterious plane, and Victor's hacking reproduced the radio signal, causing the craft to hit the Runaways' home by accident. Most of the team was unharmed, but Old Lace was killed and Klara was buried beneath a pile of rubble, and thus panicked, causing the house to become engulfed in a forest of vines.[12]
Nico was one of the sixteen super powered teens captured and brought to Murderworld where Arcade plans on them to kill each other in order to survive. She was transported there alongside with Chase. When Arcade woke them up, Nico was among those who do not attack him.
She stay with Chase and later try with her to team-up with the Avengers but when Chase quickly accused to had attacked and burned Reptil, the Runaways were rejected, and Nico, affected by the destruction of her magical tree by Hazmat, rejected herself Chase[13]. When Arcade informed the participants of the existence of safe zones, the Runaways were seen still together. At this point, they teamed-up with Cammi.
Eventually, Nico and the rest of the teens on the island. (Not including Hazmat and Reptil.) Rejoined after a conflict between Juston and Chase which was stopped by Tim. They now decide whether they wish to kill Tim or let him live, Nico was one of many to voted for Tim to stay alive, but Chase rather he be dead. Eventually, feeling she is unable to trust Chase anymore, Nico would banish Chase from the whole team with a energy beam from her Staff of One. Feeling he is going to cause more problems and make things worse with his hostile actions. Later that night, Nico agrees to be on watch, allowing Tim and Deathlocket to have a romantic moment. She is unaware by leaving, Tim reverted back to Kate, killed Juston and vanished off with the remains of Juston Seyfert's sentinel and Deathlocket.
Minoru has some magical aptitude, but she has never received proper training. So far she has relied on the Staff of One to work magic. After her encounter with Witchbreaker her abilities were augmented so that she can create smaller magical effects without the aid of the Staff. She can freely float, although this ability is not as useful as actual flight which requires a spell. She was seen moving objects with her mind to clean the Runaways new home[14].
Whenever the Staff of One is taken from Nico, she has somewhat limited powers. Her ability to manipulate magic without the Staff is greatly reduced. Also, she cannot repeat spells with the Staff or they either won't work or will cause a random effect. This was evident in the early period of the Runaways escape from their parents when Nico attempted to use the "freeze" spell she had used on Stacey Yorkes and accidentally conjured a flock of pelicans. The use of different languages and the extend of her vocabulary permit her to perform more spells.
The Staff of One: This ancient magical item has become a part of Minoru. She can call it forth by shedding blood (through cutting herself, menstruating or being wounded) and reciting, "When blood is shed, let the Staff of One emerge." The staff appears out of her chest, passing through her skin and clothing without harm. Once summoned, the staff used to work for anyone. But as evidenced by the confrontation with Val Rhymin's magician the Staff has recently developed the ability to defend itself in a violent manner. Minoru can cast spells by invoking painful memories, thinking of an effect, and giving the spell a name. There are no "standard" spells; in fact, casting any spell a second time produces an unpredictable (and usually undesirable) effect. Minoru's spells can affect the elements (earth, air, fire, water), time and/or space, matter and/or energy, light, biological processes, and mental processes, and can apparently summon creatures from other dimensions; in short, the staff allows Minoru to do anything she can imagine, short of raising the dead. After the staff has expended a certain amount of power, it disappears inside Minoru again. The Staff has been recently updated into a version of the Witchbreaker's Staff, Nico's magical powers considerably augmented.
Little more information is given to how Nico and her ancestor's meeting had ended, though the Official Handbook of the Marvel Universe's more recent edition says that Nico had "escaped" her.