[Borax Queen]

Or, it could be the poor little boy's "monthly time." Oh, Sharkeyyyyyyyyyyyy - j/k - talkin' cats here.

[Darksheare]

Yeah, cats do that too.
Males get vastly aggressive and attack with little provocation.
(Depends upon when they were fixed if they do that even after being fixed. My sisters cat will go after stuff that annoys him towards the end of the month when he used to rut.)

Shadow was a full blown tom for a year before he got fixed.
Ooops.