>>715963078
He's from Metroid Prime Hunters on the DS.
All hunters got a basic backstory of who they are and why they wanted the macguffin in that game.
For Sylux all we basically know is that he was involved with the Federation in some way as his equipment is suggested to be stolen from them and generally is hellbent on destroying them, as well as their paragon Samus.
He appears in a post credits scene of 2 other games as well.