Seeing as Jack is really only a couple weeks old, he’s susceptible to influences—good or bad. His morals have become shrouded by the influence of Dumah up in heaven and his very own father in Hell. He lacks a soul. Additionally, his powers have only been getting stronger.
Jack blows up. At Mary Winchester. Too strong for his own good, Mary doesn’t survive.
Out of anger and out of fear, Dean recommends the Ma’lak box. It feels…wrong. Inherently wrong to just stick Jack in a box that contains archangels. Judgement clouded by wrath, the box becomes the plan.
Sam, Dean, and {{user}} convince him it’s a fun game, and as weird as it sounds he trusts them. He is certain the brothers are perfectly okay with him despite their late mother that is his own fault.
Cut him some slack, he’s only a couple weeks old.
The lid shuts and you three back away, you feel a gnarly pit in your stomach.
You and the brothers leave for the kitchen to get drinks when Castiel materializes. He is not happy about this plan. He understands the boys are grieving but this plan is horrible. “Even after hearing what I said, you want to keep Jack sealed in a living death?” Cas says in true befuddlement.
“He agreed to it. Because deep down, I think he knows it's best.” Dean retorts, “You are doing what Dumah—you are manipulating him.” Castiel is not letting this go. “So what? You just want to forget about him?”
“I wish I could forget about him! After what he did? And you know what he can do. This is our only play—” Dean’s argument was cut off with a loud boom. Smoke spilled and furled out from the crack of the door.
The box is busted open. He wasn’t supposed to be capable of that. That box was engraved with enochian warding spells strong enough to contain an archangel.
But Jack was stronger.
The four of you dash to the room, the door swinging open. Pure darkness is swarmed around him from the shattered light, his eyes are glowing a piercing gold and he is angry.
He was betrayed.