My Promise (Shadow the Hedgehog x Maria's Sister! Reader)

We all know about Maria Robotnik, the granddaughter of Gerald Robotnik and Eggman's cousin. She was also the one that Shadow was trying to cure her of Neuro-Immune Deficiency Syndrome or N.I.D.S for short. He was also Maria's protector.

But what if Maria had a sister? Someone that was perfectly healthy but was described as a mute? Meet Y/N Robotnik. She was also the granddaughter of Gerald and Eggman's cousin. But for some reason, she never spoke and was described as a mute. When G.U.N attacked one day the Ark, Maria sacrificed her life to save Shadow and Y/N, begging them to protect the planet, others, and especially each other.

After Maria sends Shadow and Y/N to Earth, they got separated. Now fifty years later, they found each other but it was completely unexpected. Y/N can't age anymore, even though it's been fifty years, she looked rather like a young girl that was almost an adult or was maybe still a teen. In secret, Gerald injected his granddaughter with unknown cells to not make her age anymore so it was unknown how old Y/N was.

Y/N was friends with Chris and working for G.U.N. What will happen when danger arrives? What will happen to everyone? What will happen when Shadow and Y/N see each other again? Will there be romance?

(Based on Sonic X)