William killed the kids as per canon, but Henry covered it up.

He lost Charlie and could not bear(heh) to lose the company and the pizzeria.

So Henry covered up the deaths and personally removed the kids remains so no one would find out.

This all changes when Henry finds out William killed Charlie.

After William destroys the animatronics, Henry confronts William.

Henry lets William have it. He blames him for Charlie's death and all the kids who died. William retorts by saying he could've stopped this anytime he wanted, but couldn't. He was blinded by Freddy's and his love for him, just like he is. The aura is too great to let go over something as simple as morality. He tells Henry why he did it, his discovery of remnant and how they can not only live forever, but bring their children back. Henry calls him insane and a fucking monster. and all William can say. "what kind of monster hides the evidence to keep our business a float?" "After all this time, my old friend, you don't get it do you?" "What are you talk-" "Why, you're my accomplice. I kill the kids, YOU hid the evidence. YOU protected Michael and pinned my boy's death on Michael's friend. YOU removed the bodies from the animatronics and you kept the old Fazbear Entertainment spirit of ignoring everything. You are every bit of a monster as I am, the only difference is I don't hide who I am" "FUCK YOU WILLIAM!"

and then it happens. the ghost of the children appears.

William panics and tells Henry to put on their suits on. Henry questions why, William tells him they wouldn't hurt "one of them"

William laughs and reminds them "I'M ONE OF YOU"

William continues to laugh only to have a bit of rain to fall and cause the springlock.

and as Henry is about to take the suit off. Charlie appears.

"Daddy? Did you really help HIM?

"Charlie? Is that really you? I-"

"DID YOU HELP HIM OR NOT?"

"...I'm sorry, you died and all I had was Freddy's. I couldn't lose this place. I'm sorry"

and after that, the ghosts push Henry into the visible hole for the rain to pour in and cause the springlock failure.

William and Henry now trapped together for 30 years.

William becomes Springtrap, while Henry becomes Beartrap.

Henry can't bring himself to kill William. William won't kill Henry because his punishment is too perfect. "Like it or not, we're partners from beginning to bitter end, YOU'RE STUCK WITH ME HAHAHAHA"

William kills, while Henry protects.

Henry saves Michael and keeps William in Fazbear Frights while they burn.

Now who is helping Mike end it all in this au?

Charlie. Much like the FNAF VHS tapes by he who must not be named, Charlie helps Mike end it all and a chance to get redemption in the end while Mike helps Charlie free the children and get revenge on their fathers.

William is Scraptrap, while Henry is Scrapbear.

Art bys Shadowof1987

Henry foolishly tries to stop William and Elizabeth from hurting the children.

Scrapbear's lines

"I just wanted to protect Freddy's"

"Please let me die"

"Charlie, please forgive me"

"Mike, I'm sorry."

"Your father is a monster, please end my suffering and this nightmare"

Mike is the one who gives the speech.

"DON'T KEEP THE DEVIL WAITING, FATHA"

"And to Henry, I couldn't believe it when she told me what you did. But now you're reunited and she's going to make sure you burn in the business you are oh so proud of that you kept so many suffering families from their loved ones remains. Goodbye Henry."

queue an image of The Puppet holding onto Scrapbear while they burn.