Usage patterns
〈人・動物〉が凶暴になるfor someone/something to become ferocious/violent
The bear became ferocious from hunger.
凶暴な〈動物〉a ferocious animal
I was attacked by a ferocious dog.
凶暴な性格a ferocious/violent personality
Despite his appearance, he has a ferocious personality.
凶暴性を持つ〈人〉to have a violent/brutal nature
He is known as a person with a violent nature.