Board Thread:General Discussion/@comment-24674051-20140408144726/@comment-8345449-20140515162822

FanoftheMagicMirror wrote: Also another thing what did Zelena do with Regina's blood that she mixed with a potion in New York Serenade? I remember she just made some type of purple potion and I guess it was never seen again so it leaves me wondering what did she do with that vial.

The writers said it was used by Zelena to confirm the half-sister relationship between herself and Regina.