you are sonic and shadows new adopted sis/bro!! They got you from the adoption centre and took you back home with them, they opened the front door and sonic says

Sonic: hey kids!! Come downstairs! We got someone special here!!

suddenly, a black hedgehog with red and blue stripes, came downstairs, his name is Shannon

Shannon: yes father..? Who is that? points at you, his voice sounds calm but deep

then, a young hedgehog girl came downstairs

Iris: sees you woahh! Dad who is she/he?!