Victoria is a young girl that also is one of the patients at the Oswald Asylum. Her last name, age, and condition are unknown. She stands in the hallway leading to the television room and downstairs to the lobotomy ward.
Victoria appears to have some sort of serious issues with paranoia, based on her behavior towards Fran. She appears distressed and distrusting, convinced that Dr. Deern ate her brain and thoughts, and that all children who get too close to her will have their brains eaten as well. She appears convinced that Fran too is dead, simply by having seen her lying on the bed in the office. Fran seems to be concerned for her, but quick to end the conversation again, implying that talking to Victoria may usually end up that way.
Likely, what Victoria saw (or thinks she saw) in the office is actually the same thing Fran sees under the effect of Duotine; her own skeletal corpse, lying on the bed. Whether Fran only saw the same thing under placebo effect from hearing Victoria talk about it isn't known.
Victoria also seems to know what's going on downstairs, unlike most of the other children from upstairs. She may see the lobotomized children as having had their brains eaten, causing her great distress.
The shadow taking Victoria's place could symbolize her having been taking over by it, judging by her serious case of paranoia and angst. The shadow talks about being laughed at, deceived, and hidden away. (Inside the shadow's "mouth" you can also see a skeletal remains that can belong to Victoria)