Disclaimer: Ouran doesn't belong to me...yet...
Hikaru
Unlike what most people thought, Hikaru was not ignorant. He did not miss the betrayed look in his brother's eyes when he went to Haruhi instead of his twin. He did not miss the tears his beloved twin shed in the shadow of the night. He did not miss how fake Kaoru's smiles had become. He did not miss Huni-sempai and Mori-sempai's disapproving looks. He did not miss how Kaoru barely spoke to him anymore, other than to do their "brotherly love" routine. He did not miss any of this, but he didn't notice it either.