William taught Nathan to use magic only under his watchful eye. It was unpredictable and dangerous when not handled properly. He taught him to keep his ability a secret, even from his friends. But most importantly, William told his little brother to never trust government personnel. The government seemed attracted to Mt. Ebott, which is unfortunate, as their small town happens to be at the base of it. Most people thought that it was the high concentration of magical energy surrounding the mountain, but others speculated it was to make sure people didn't wander where they weren't wanted.
Nathan had once asked William why government personnel were so dangerous, and William told him that they would take them away from home. Somewhere that wasn't pleasant and would do horrible things to them. Despite this, William always told Nathan that their magic was not a curse, but a gift, and that he should always cherish it.
For Nathan's eighth birthday, William gave him an orange bandanna. Words were stitched onto the cloth in black thread: "The bravest, the strongest, the hero". Nathan had held it in his hands, his bright orange eyes glistening with happy tears. He had tackled William in a hug, of which he had been hugged back. William lifted his hand and ruffled his brother's short, auburn hair. From that day on, he only took it off to wash it or to clean himself.
Nathan disappeared on the night their parents had left years ago. William had asked around for months, desperate for answers. Since the government agents didn't really care, William was left to search the mountain by himself. He had nearly fallen down the hole in the mountain when he stumbled on one of the many vines surrounding it. The only reason he didn't fall was pure luck. Every time he visited that mountain, he made sure to bring a flashlight and paid extra attention to his surroundings. William climbed that mountain every day after his brother's disappearance.