Just think, we could have avoided this whole game if Shadow just asked Rouge what happened in his past.
Except Rouge has no idea who Maria is, the main reason Shadow wanted his memory back. The only one who knows about Shadow's past completely is probably Eggman, who can't be trusted.
This is something that annoys me about some Sonic fans, yes I don't like that they made Shadow ow the edge incarnate either, but thinking that asking Rouge would help Shadow learn his past is rather silly.
And no you can't tell me, but Rouge as a gun spy, she has access to GUN's data, her access to data is limited, meaning that again only Eggman can give Shadow a full view of his past, and Eggman can't be trusted so it won't be happening.
Now what is stupid is everyone not telling Shadow, you helped us protect the world before, help us again by fighting these Black Doom guys.