Sephiroth is depicted as Cloud Strife's archenemy, and is seen as a symbol of Cloud's troubled past that haunts him. Sephiroth is a former renowned SOLDIER, who became twisted. Before his fall from grace, Sephiroth was one of the most lauded success stories of the Shinra Electric Power Company's SOLDIER program. His successes in the field of battle during the conflicts surrounding Shinra's bid for global domination led to his status as a celebrity war hero and the poster boy for both the Shinra Military and the company's SOLDIER program. Learning of his true origins drove him insane, causing him to be driven by a desire to destroy the world. In this game he serves as a secret boss, but Smash Ultimate's latest reveal at the time of this post, has inspired me to give the dude a slot for this fangame as well! Curse you Sakurai! XD

He sounds malevolent, cold, calm yet intimidating.