I’ve seen enough people interpret this scene as “metal realizes he’s not the real sonic” and might as well give my thoughts on it because I very, VERY much disagree to this
Metal is not “realizing he’s not the original” because he KNOWS this. He knows that he’s not literally Sonic the Hedgehog. He insists that Sonic is the copy because he is the better Sonic, and as such more worthy of being “Sonic”
He KNOWS that he’s a robot, and in fact, he doesn’t have any issues with being a robot. He takes PRIDE on being a robot, because he thinks that’s what makes him the better Sonic: stripped away of the biological disadvantages pf his flesh counterpart. He’s immortal. He cannot be harmed in a way that matters. He cannot get tired. He does not have any moral restrictions when fighting. And if anything goes wrong he’ll get improved upon and come back better.
The point of him is that he can do EVERYTHING, and I mean EVERYTHING sonic can, but better.
So… what did THAT scene meant then?
It meant that he failed at being the superior Sonic. He sees Sonic struggle with the metal virus, and thinks of himself being more capable of surviving it than Sonic. He believes himself more capable of managing the virus and wants to prove it.
But of course, that doesn’t work. He can’t be better than Sonic at surviving the metal virus if he can’t even infect himself. And it’s not even at any of his fault: it’s not like he chose to be a robot, and for the first time ever on his life, being a robot proved to be a disadvantage.
But also (ALSO) let’s not forget what the metal virus is truly for: making zombies?… yes, but most importantly making slaves. Making brainless, mechanical slaves that will (theoretically) do anything you command them to do. The point of the metal virus is stripping a living thing out of its autonomy and freedom
Then, what does it mean that the metal virus slipped right through his fingers unaffected? That there’s nothing to take away from him. He’s, in spirit, already a zombot. Already stripped away from everything, already perfectly obedient, already a mechanical slave.
And he failed at being the better Sonic because Sonic DOES have that autonomy and freedom. He’s alive, he’s real, and he actually has something to lose from the infection, while there’s nothing to infect at all with Metal. Metal can’t fight away the metal virus better than Sonic, because he has already been infected since before the virus was created.
The previous arc, Eggman’s reprogramming had momentarily tricked him into being complacent to Eggman. Tricked him into accepting Eggman’s orders as absolute and happily do everything he’s told to do. He’s stripped away from his ambitions, now his plans revolving around giving Eggman back his power, and he was oblivious to it all until this point in the comics.
I mean, why do you think the conic ends with Starline ordering him around to get back to work? Because he’s going back to the role he just confirmed he has: the mechanical slave.
And as such, what he truly realizes in this scene is that Eggman won.