Board Thread:General Discussion/@comment-26391241-20150511234157/@comment-15736398-20150513015046

The things we know for sure about the Darkness/Curse of the Dark One are:

1) It corrupts and destroys

2) Merlin/The Sorcerer tethered it to a human soul in order to keep it in check

3) Both of the previous Dark Ones we've seen had glitter-scale skin

4) Both of the previous Dark Ones we've seen went after the Sorcerer's Hat (Zoso for unknown reasons and Rumple because it was key to freeing himself from the influence of the dagger)

Also, for the record, Rumple wasn't looking for power when he killed Zoso (he was simply looking for a way to keep Bae safe), nor did he actually crave power after being Cursed (notwithstanding other characters' opinions to the contrary).