Elio metaphorically lost the light in his eyes - leading to a much duller expression, and was mute for a time. They were the result of his "re-education" via his "special classes", and clear signs of the severe mental trauma that inflicted on him, which took some good years to mostly recover from.

So, while he had re-undergo the same character development that led to him discovering his emotions - albeit under a different context and linked to different settings, he learned and predominantly used sign language for a good amount of his time under his assigned Aura master, and later during his time with TUA - up until his third-year, where he and his close friend, Artemisia made profound breakthroughs in their respective mental health journeys.