As far as I know, the word "Brutal" means intolerant, mean, and heavy handed. But more, it implied treachery.
"Et tu Brute'?" were Julius Caesar's final words as he saw his old friend murder him for political gain. What good did it do them, as they knifed their former friend and then spread his blood all over themselves? Rome was a savage place, where crucifixion was the worst way to die but they also put Jesus to death on that hellish thing -- at the demand of His countrymen!
When you think of all the rottenness that humans do, remember that "brutal" also means "treacherous."