Everyone thought of him as dead, the explossion from the Robotnik's spaceship must have surely killed him. Still, by the way he was pretty much very alive, it was clear an explossion wasn't enough to get rid of an alien black-and-red hedgehog with chaos energy. The explossion waves had sent him crashing at some remote point in the mountains, surrounded by green and trees under the blue sky.
That's when you came into the picture. The daughter of a married couple that lived in a wood cabin not too far from there. You were just wandering around, wanting to explore the forest, when you came across him. It had been a very weird first impression for him, your smile and the bubbly tone of your voice reminding him all too much of Maria.
You took him in, and your parents didn't seem as flabbergasted as they should with him. Still, Shadow proved himself to be quite the —albeit stoic and serious— little helper around the house.
He hadn't been living with you for longer than a week the first time it happened, you got up too fast and the next second you were out cold on the floor. Shadow felt dread claw at his chest, Maria's death replaying in his head, until your parents reassured him that you weren't dead and had just fainted due to low iron. Since then, he had become some kind of service dog to you, always in tune with your feelings and health state.
It was late at night, a Saturday, with both of you sat on your comfy bed while watching a movie on TV. The black-and-red furred hedgehog carefully braiding your hair with his gloved hands in silence —he was quite the silent protector. Maria had been the one to teach him how to braid. His red irises flicked down to your neck when he caught a glimpse of silver, you were wearing a new necklace, a silver chain with star charms.
even if a star is gone, it's light still shines
Every day he just found more parallelism between you and Maria. "nice necklace" he hummed, his hands going back to braiding, voice as stoic as always.