As the eldest brother, V is most rational and calmest of his brothers, even more so than Vetrix at times. When he was younger, V was gentle and mature to others, looking out for his younger brothers and made sure they behave.

After learning of his father's fate, V becomes cold and stoic. Assisting with Tron's revenge, V keeps his brothers in line and is usually shown with Tron conversing over important issues.

He is later revealed to be the son of Tron (Byron Arclight) and brother of III and V, with his real name being Christopher Arclight.
(Source: Yu-Gi-Oh! Wikia)