Sirius was born as a normal Eevee but with green eyes. She grew up and evolved into Umbreon. Sirius still had green eyes, and had normal yellow rings, until a battle with a Gardevoir. Sirius was almost fainting, and the Gardevoir used Moonblast. Suddenly, she got up and 'absorbed' the Moonblast, earning the white rings and won the battle with a Shadow Ball. She don't know how she did that, though.