I know the look well. And the sheer size of an animal can be very intimidating. With range beef it is always the cows with calf that are very aggressive more so than the bulls.
As I was growing up my Grandmother had to keep reminding me that man could once take down mammoths and mastodons. It kind of mentally helped a bit with the size intimidation. lol
This just brought back a whole bunch of funny memories... :)
I remember reading a James Herriot (of All Creatures Great and Small fame) story some time back about where he talked about a bull calf he had delivered.
The calf became his best friend...when he drove up, the calf would come running up and gamboled about him...even well into adolescence, just the chummiest animal that could be.
He went for a stretch of some months where he didn’t visit that farm, and when he did, sometime in that interval, the calf had turned into an adult bull.
He had been called to place a nose ring in the bull, if my memory serves me correctly.
When he approached it, He was startled by the dramatic change in the animal, even apart from being fully muscled and brawny...it reeked of aggression to the point of hatred. When he looked into it’s face, the calf with the doe-eyes was long gone, and a “glittering malevolence towards all things human” (including him) now looked back at him.
IIRC, the bull, his former chum, nearly killed him when it got loose as he was performing the procedure.