A disabled child. Far and away most likely.
A kid with disabilities, according to a World Health Organization study published in the Lancet, is four times "more likely to be a victim of violence", including sexual violence, than any other potential violence victim. Most often a child victim already suffers from mental illness and/or retardation and it's far worse for a hospitalized or otherwise institutionalized child.
The Lancet aggregated the results of seventeen sutdies culling evidence on over 18,000 first-world children. All of the victims were living in what are considered wealthy nations, "from the United States, to Europe, to Israel." In the world's richest nations, roughly three-percent of children are disabled; (the percentage doubles in poor countries.)
Well over 50,000 disabled children are murdered yearly across the world.
Theology be damned: when you are a child's enemy, there is no redemption.