Brutes are what orruks become when the fighting is good: hulking slabs of green muscle in jagged iron, too big for fear and too strong for subtlety. They wade through lesser enemies with the bored efficiency of workmen clearing brush, and only wake up properly when something their own size — or preferably bigger — finally hits back.
Brute society is a ladder measured in krumped things. A Brute who drags down a gargant or fells a monster earns a swagger no boss can take away, so every mob is perpetually scanning the battlefield for the biggest thing on it to test themselves against. Their favourite insult is 'little,' their favourite tactic is forward, and their idea of respect is hitting you hard enough to mean it.