I'm following you until the end, Zack!
Luxiere is a SOLDIER 2nd Class, and a friend of Zack Fair. He plays a small role in Crisis Core -Final Fantasy VII-, acting as Zack's email buddy, and considers Zack as his idol. Although Luxiere claims to be loyal to Zack and will follow him to the end, he does not seem to be near as loyal as Zack's other friend, Kunsel. Kunsel mildly hinted that he would betray or leave Shinra to help Zack in his last emails.
Luxiere, on the other hand, stated in his last email to Zack, that if he were allowed to catch Zack, he might get a promotion and use his "new found authority" to help Zack. Although this might have been a ploy to get to a higher rank, Luxiere might have truly meant to help Zack.
Luxiere can be seen for a small time on screen briefing Zack about a new development in the Shinra building.
Luxiere's fate is unknown after he hears Zack is killed in action after his mission in Nibelheim.