Suguha Kirigaya is the cousin of Kirito (or Kazuya) as all anime fans have come to understand from season 1. Shoto’s personality is nothing like his abilities with the exception that he seems cold, aloof, plus unconventional and introverted. I’m not sure why the designers decided to not make his right eye red to match his fire abilities, but they went with grey instead to avoid doing the obvious thing it looks like. In his right eye though his eye is grey which is why he’s on this list. And this reflects in his left eye which is blue, matching his ice powers. Here’s a list of anime with characters just like that….
That said, characters who are less flashy tend to be the ones with grey eyes but can sometimes be the flashy/flamboyant type. Anime characters with grey/silver eyes are rare no matter how you wanna look at it.