After his life-saving surgery, which involved having eight Chaos Inhibitor Gates implanted directly on his spine, Will discovered he could unlock more power than ever by opening all eights at once, which gave him five minutes of energy, with the gates locking open if he used Chaos Energy from other people. (More on the effects of the Overcharge ability at it's page) In his base form, by using that technique, he discovered he could actually change into a brand new form, which he called Overcharge, after the ability.
Flashfire212's fanfics Edit
Will first transforms while training with Sonic and Ronan. Ronan warns him about opening all eight gates, but Will does it anyway, blowing both of them away with the sheer amount of power radiating off his body. After the five minutes though, he collapsed, unconscious. Maddy was able to revive him with ease, but she worries that he'd become addicted to the power triggered by opening all eight gates at once. He promises to only use it in dire circumstances, although he thinks he might use it a bit more than that.
The form itself hasn't been seen in ages, but it is planned to appear during a number of the duels between Will and Shadow in Book Four.
So far, Overcharge Will hasn't appeared in any games, although he can at the game designer's request.
Overcharge Will appears exactly the same as Will, but is generating a similar aura to One-tailed Transformation.
Overcharge Will has all the abilities of Will's base form, with WAY more power. Will has some control over the aura, being able to create body parts like tails and arms out of it with ease. However, the aura can also retaliate and gives him immunity to fire-type attacks, leading to the believe that the aura has a mind of it's own.
Personality Change Edit
Like Fleetway Super Sonic, Will undergoes a personality change. He becomes extremely cocky, and will claim to be invincible. If he locks the gates open, he believes he is undefeatable, which is believable considering the sheer power of his attacks and aura. He acts more like an animal than normal after twenty minutes (with gates open). This is the only form where Overcharge triggers a personality change.