Board Thread:Lore Discussion/@comment-10993011-20140918001226/@comment-10993011-20140918024040

Harold Burned-Mane wrote: A blog I made on the same subject.

I actually think that she may be the actual child of Barenziah and Tiber Septim, or the child's daughter. An interesting fact is that Katariah and Barenziah were from the same house, House R'Aathim. This is awesome, thank man.

But, for all we know, Barenziah and Tiber Septim's love child was aborted (unless the author of The Real Barenziah wasn't accurate, which is entirely possible. Especially as they were about the Nightingale)