When Dean leads him into the bunker for the first time, Cas bounces off the entryway and disappears in a flash of light. Dean wrings his hands anxiously until forty minutes later, when Cas reappears looking embarrassed and ruffled.
“You okay?” says Dean, leaping up from where he’s been sitting against the door frame, his head bowed in prayer.
“I should have remembered that the Men of Letters took the protection of their strongholds quite seriously. I cannot enter.”
For the first time, Dean notices a line of tiny sigils inlaid in the door frame. He frowns at them.
“On the bright side,” says Cas, “these wards are very old and very powerful. They will keep you safe from all manner of unsavory creatures.”
“You’re not unsavory,” Dean pouts. “Can’t we write in an exception for you?”
“I wouldn’t advise it,” says Cas, running his fingers gingerly along the sigils. “The spell is quite intricate. I doubt anyone but the original caster would have the skill to alter it without disabling it entirely.”
Dean mulls over his options for no more than a second or two before saying, “Okay.” He pulls a knife out of his pocket, flips it open, and scratches the ornate sigils away.
“Dean!” Cas protests, but it’s too late. The wards dissipate with a crackle of static in the air. Cas puffs up like an indignant bird. “That was very unwise.”
Dean stretches his hand across the threshold and pulls Cas inside. “It’s cute that you still expect me to be wise,” he says. “Come on, you gotta try this shower.”