Cas is walking with Dean down the main hall, reading through the assignment requirements for an essay due in his English Literature class, when a familiar voice shouts, "Dean!"

The arm around his shoulders tightens there to bring him to a stop. Dean smiles sunnily as a streak of red hair announces Anna's presence. She barrels up to them and grins at Dean, eyes shining.

"Hiya, squirt," Dean says easily. "What's up?"

Castiel blinks. When did Dean and Anna become friends?

"I wanted to say thank you for the advice," she says, fast and breathy.

"Did it help?"

She nods enthusiastically. "Yeah, it worked great! Just like you said it would!"

Dean ruffles her hair, and Cas watches in bewilderment as his gentle, softspoken little sister blushes and giggles as she bats his boyfriend's hand away.

"I'm glad," Dean says fondly. "Now get outta here. You're gonna be late, squirt."

Anna nods, pauses awkwardly, then flings herself forward and hugs Dean fiercely before waving at Cas and darting away. Dean blinks, then chuckles and resumes walking them toward their physics class.

After no explanation is forthcoming, Cas says, "What the hell was that all about?"

Dean shrugs. "Some girls in her grade were giving her shit. She asked for some help with how to deal with them." He smiles a little. "I'm glad it worked. She's a sweet kid."

Anna is barely a year younger than them, but that's not what has Cas frowning.

"Why did she ask you rather than come to me?"

Some of what he's feeling must be in his voice, because Dean whips around to look him in the eye.

It's just that… Well, Castiel is well aware that he's not the most approachable person on the planet, but he's always considered his relationship with Anna a close one. He really quite adores his sister, and it stings that she didn't feel like she could come to him if she was having a problem.

Dean's face softens and he pulls Cas into their almost empty physics classroom. He moves them into the back corner, and their reputation is enough to keep anyone from moving closer.

"Baby," Dean says sweetly. "Anna loves the shit out of you, you know that. You're her hero."

Cas blinks again. Her hero?

Dean is still talking. "She looks up to you, Cas, so fuckin' much. I think she just didn't want you to see her struggling. She doesn't want you to think she's weak or something."

Cas let those words sink in. It makes sense, he supposes. He has been Anna's main defense against their harpy of a mother since before he can remember. And though they are close, both personally and in age, the gap between their actual ages has become more apparent thane ver as he prepares to graduate.

He nods. "I'm… Relieved, then, that she feels safe talking to you about such matters."

Dean's lovely green eyes shine with emotion for just a beat before he gives Cas that cocky grin that he hates/loves/craves.

"Yeah, I'm the Novak whisperer."

Cas snorts inelegantly and revels in the laugh it pulls from Dean.

Later that night, as Cs readies himself for bed, Anna appears in his doorway.

He sets his book down on his bedside table and turns to give her his full attention as she hovers there, almost nervous. They're both in their pajamas, though, and somehow, without the armor of their proper clothes and perfect grooming, it's easier to be vulnerable this way. Easier to talk to one another.

"Anna?" he asks.

She nods. "I just…" She seems to brace herself. "This is stupid, but I just wanted to tell you that I really like Dean, and I think you're really good together." She speaks so fast the words bleed into one another, but Cas understands her perfectly.

His heart warms, and he gives her an honest smile, the one he saves for her and Dean alone.

"Thank you, Anna," he says, voice low and heartfelt. "That means a lot to me."

Her answering smile is like sunshine.