I can’t believe another sick kid would do something like this deliberately — I think it’s more likely to be the result of carelessness, not a deliberate action.
Good thing it was found in time to take the kid along.
I can. The vast majority of healthy kids and the vast majority of sick kids are nice most of the time. However, I have seen healthy and sick kids stray in the other direction, either because they were particularly grumpy that day (completely forgivable with cancer, given the pain) or because they were just that way by choice. I spent a couple of months in a major children's hospital, much of it working with the kids or just playing with them and reading to them. They're kids, not angels.