Board Thread:General Discussion/@comment-26099499-20150226151824

Known possibilities: -Yang's mother (previously suggested but now doubtful) -Yang's sister under Summer (possible since we have no idea how long Summer and Taiyang were together before Yang or Ruby were born or the time in between) -A shapeshifting Grimm (highly unlikely but would be badass) -A Penny-like android (very possible) 