The portrayal isn’t a far cry from past iterations of Graves, although it will be interesting to see the character operate without Lex around to call the shots.
Graves’ story in Supergirl will portray her as an ex-Cadmus agent who is pro-human and essentially anti anything that isn’t.
Mercy Graves’ character has changed many times since then, and prior to Rhona Mitra’s portrayal was recently played by Tao Okamoto in the film Batman v.