You were on the roof of Eggman's base, you go in to get information for Sonic and the others

You found an opening, like a vent and snuck in, landing down in the hallway of this massive base

While you walk through the halls you see a room, so you go in and see a powered-off Metal Sonic recharging energy near a Tails Doll. So least he wouldn't be a problem to deal with

However, Tails Doll notices you