Pester is a member of the Morlocks, outcasts who were a community of mutants who lived in tunnels beneath New York City, she was an outcast primarily because of her diminutive size.
While most Morlocks had been killed in the mutant massacre some escaped, a few with the help of the X-Men and the original X-Factor team. Pester and along with family came across Anna in the old Poseidon, where she help take care of Pester's baby.
Until one day when Spider-Man came to investigate the several mysterious happenings in the hotel. He thought the Morlocks were threatening Anna’s baby but after he decided to 'rescue' the baby, he found out that the baby belonged to Pester, who calls the child only as baby.
The villain Firebrand attacked the fundraiser above which caused the building to collapse, killing Mother Inferior in the process, Pester was horrified until Ent saved the rest of his family as the broken water pipes began to flood the basement with the help of Spider-Man. Ent was able to convince Pester to go to the surface where they found a new home with the local homeless.
It is unknown if she kept her powers after M-Day.