I've only seen the episode once but I thought I saw Percival standing there in the crowd at Gwen's coronation. I'd have to rewatch it to be absolutely sure, but if that's the case I could see him bringing the news of Arthur's death to Camelot (since it seemed like he was following Morgana, so that should've led him to Avalon) and then leaving Camelot himself, perhaps to go on a major quest like his legendary counterpart did.