Masks
He'd never admit it on his life, but there were days that being the anti-hero drove Meta Knight crazy. Other heroes got people cheering for them and smiles. He had to not only help save the world, but also do it while wearing a mask (no, not the physical one), which was double the work, and what happened? People gave him blank stares like he was from another planet (even when he wasn't) if they weren't afraid of him.
But selfish and fame catching was no more who he was then his other mask, so who was he really?