"Anybody who can attack someone like that is dangerous," she said.
The attack happened in a city-owned pedestrian concourse outside the westbound SEPTA subway platform at 13th and Market streets on Tuesday afternoon, where, police say, Oberlton stomped on Derrickson's head so severely that he remains in critical condition at Thomas Jefferson University Hospital.
Chernia Williams, 26, the woman who shares children with both men, said it was a cowardly move.
"[Oberlton] walked by [Derrickson] plenty of times, but never said or did nothing to him," she said. "He caught him by himself and he pounced."
Williams has a 2-year-old daughter with Derrickson, and an 8-year-old girl and 5-five-year-old boy with Oberlton.
Others are torn as to whether Oberlton is responsible for the beating, but Williams and Derrickson's mother, Anita Cross, said that they have no doubt that he's the culprit.
"He couldn't accept the fact that I cut him short for Najee," Williams said, using Derrickson's middle name.
The conflict between the two men began almost four years ago, after she ended an abusive two-year relationship with Oberlton, Williams said.
"He used to bite me on the arms," Williams said. "I had to get out."
She left him in 2002 and the following year, a friend introduced her to Derrickson. Since then, the two have been inseparable, she said. And her other baby's father didn't like it, she said.
Derrickson still must breathe through a ventilator; a cranial monitor he's hooked up to gauges brain swelling. Despite his condition, Cross said he'll pull through.
"He can hear me now," she said yesterday as she leaned over his pillow. "The other day, he squeezed my hand. He's going to get better." *