Disclaimer: Doctor Who does not belong to me. It will never belong to me.
1st Doctor.
He had left Gallifrey for Susan or at least that's what he told himself. He had done it to save her from a society that had ruled too long without change and had become stale.
He tried to forget that in reality he'd left because he wanted to save himself from becoming forever etched into a stale and stuffy society.
He'd dragged Susan along because he hated to be alone and he feared as his granddaughter she'd suffer the backlash because he stole a Tardis, ran away from his own people and everything they stood for.