(Note: It's advised to read the last post's text if you wanna read and fully understand the text here, but it is not necessary and in either case you don't have to read the text if you wanna just look at the art. That's fine.)
So do you remember in my Modern Sonic post my lil explanation for green eyes? No? Because this post was made like five minutes after that post? Yeah that makes sense.
Well, there I gave Modern Super Sonic green-shifting-to-red eyes to represent the amount of Chaos Energy in him that is stable and controllable for him being at its limit--this post is about what happens when Sonic goes past that limit, and what happened within the first couple of times of classic Sonic going Super in this version of him that weirdly combines things from various continuities and a few headcanons to make its own lore.
There are two things that can happen when someone has too much energy. Either their body is destroyed in a sudden burst of uncontrolled Chaos Energy that threatens to tear through everything around it until it dissipates... or you hit that little spot where it's too much for the user to handle, but not their body or the connected source of that energy.
What happens then is that the energy itself takes over the user during their unconscious state, with one main goal--expel as much Chaos Energy as possible to return to a more stable state, with no regard for who or what is hit by that energy in the process.
Normally this state doesn't last very long, as that energy can be expelled rather quickly. The only problem is if you're receiving Chaos Energy from a *really* powerful source that can and will continue to supply just as much energy as is being shot out.
Like the Master Emerald.
Our version of Sonic, who still wasn't as experienced in controlling high levels of Chaos Energy, may have tried to go Super with the Master Emerald once. When that wave of energy first hit him, it did send him into Super, but it became so overwhelming that he was knocked out immediately, forcing the Chaos Energy within him to take control.
With its extended existence from it being unable to remove enough energy from itself or disconnect from the Master Emerald (as the energy controlling Sonic came directly from it), it ended up developing a personality built on the hedgehog's, twisted with a strong desire to destroy and wreak havoc.
A sentient monster who'd quietly remain in Sonic for years to come, hiding in the traces of Chaos Energy left in his body after the fact and only growing more powerful with him over time.
...Yeah I basically just put Super Sonic in the Fleetway Comics in my lore as a variation to the regular Super form. The extended explanation above was probably not necessary provided that we know who this guy is already. Oh well.