Board Thread:General Discussion/@comment-11276487-20130724234237/@comment-13446185-20130806210419

Look up Shezzarine on the UESP wiki. read the very bottom. The developers themselves have said that Tiber Septim is related to Lorkhan. Since the diety Talos is formed out of more than one Shezzarine (Underking and Tiber Septim) he most certainly has enough identical traits to Lorkhan to mantle him.