Light Yagami/Harry Potter
Light watched as Petunia raged. She had been proven wrong in front of her neighbors and family friends within moments of opening her mouth. She made excuses, trying to make it seem as if Light was a troublemaker and harassed Dudley and "Oh that boy, he's touched in the head. Can't even say Dudley's name properly, can't string along more than two words. The trauma from the accident, you see."
She didn't know that Light was an actor, a 'monster who lies, the worst of them all' in L's words. He shyly hid behind Dudley whenever an adult spoke to him and otherwise stoically ignored them.
'Trauma', hah! Most of Petunia's acquaintances believed that she had been scammed by a hack doctor and that Light was just an extremely shy child.
And oh, how Petunia raged. She fumed and paced and insulted Light with even more degrading names before cutting Light's perfectly healthy portion of food to half. It took Light a few days to figure out what Petunia was doing but he caught onto it on the third day.