Experimental {Sonadow}

What if Sonic was captured at a young age by Doctor Robotnik? Experimented on to the point he could barely keep up. He was always on the verge of passing out after each experiment. Until one day someone found him and saved him.

This is just an A.u I came up with while trying to go to sleep.
So a little backstory of this A.u is that Sonic and Shadow already knew eachother before Sonic got captured. He also knew everyone else too. But when Robotnik got him everyone searched cause no one knew that Robotnik had taken him. Robotnik would attack only one more time to make him less suspicious of taking Sonic asking where he was and what not. But Shadow never believed him. After about a few years people lost hope in finding Sonic all but Shadow the Hedgehog and Tails they wouldn't rest till they find their once beloved friend and brother.