An evil stare? How intriguing
Actually it rang a bell for me. I've only ever seen it once. Taught easily a few hundred teeny tinies of pre school age over the last couple of decades. But just in that one case alone have I seen a child so young (he would have been a few months shy of three) actually engage with that kind of look/stance.
I don't know what was behind it, or if he grew out of it etc. The contact only lasted about six months. But he would fix his "prey" with this intent stare, and (given his age) it was really disconcerting the look that went with it. He would wait, maintaining a malevolant stare on the kid he had in his sights. Then he would attack. A push, a wollop, a snatch of a toy, all fairly normal kinds of toddeler style physical stuff. But the look and the real sense of him picking a victim and waiting for a good moment to pounce, with that look on his face, made the hairs stand up on the back of my neck. Cos it was totally unlike anything I'd seen before, or since.
It didn't go unnoticed by mums, staff, and "evil" was used to describe the intense stare. I can't reconcile evil with a 2 year old, but there was something.... extremely unsettling, about the way all the elements came together and that look in his eyes was the clincher that took it way out the ordinary.
It might well be that the OP is seeing more than is actually there cos her view is coloured by having to see her kid get hurt or upset without parental intervention. But it's not impossible that it's an emotive, but not altogether unbelievable description of what she is observing.
With any luck the kid is just going through a Stare of Death phase.
Gives me the willies just remembering it. It was so wierd, and looked all wrong for a kid so small to have the ability to use his face and eyes like that.