Board Thread:Lore Discussion/@comment-26316533-20150415233335/@comment-121511-20150416135105

Can't recall exact sources at the moment, but it's a conclusion commonly reached based on various texts on The Imperial Library, namely mentioning Tiber Septim's "many heads", his penchant for seemingly being in more than one place at the same times, and the fact that while Hjalti was the public face of the Emperor, Wulfharth still served as his trusted General and Arctus his trusted Adviser/Battlemage.