Not even kidding, that's the story of Attila. He was originally a hostage against his father and every single week was amazed at how weak the Romans appeared to him with even the Romans describing him as an extraordinarily punchy manlet but with a restrained attitude. One of his first major acts after his return was to convince his brother Bleda to incorporate Roman siege rams and towers into their Hunnic banditry, turning them from an annoying threat that the Romans ignored because of their tall walls to an apocalyptic plague.