Let this be...
Fear wasn't something that Leonel could ever remember feeling, or at the very least, any memories of when he was were completely unimportant because he had likely been too young for it to matter. Even when the Metamorphosis descended onto Earth and he was thrust into life and death situations almost immediately, he had never really wavered in such a way.
He could remember his first entry into the Mayan Tomb quite clearly, and although he had felt apprehension, fear wasn't really at the forefront of his thoughts. In fact, the boldest emotion he remembered feeling from that time was guilt due to the lives he had taken.
Even back then, he was calm and cool under pressure, able to use his smarts to get him out of situations he otherwise had no business getting out of. By the end of those few days, he had become a war machine, killing with every step and using those olden guns as though they were pistols.