Not a lot of Castiel in the house indeed. He has necessities, as if he's living on the road instead of in a small but nice house with his dom. He's not earning much, true, but enough that there should be more. He has what he needs, nothing more. Jason has gotten him gifts, yes, but Jason has also handled Castiel's money - for practical reasons initially, as Castiel had no clue about setting up or using a bank account on his own, or how to make a budget, how to take proper care of himself in every way.

So he has what he needs. There's a side of the shelf that clearly belongs to him - the clothes he wore when Dean and Sam finally found him, his work clothes, some spare clothes, underwear, cheap collars, socks, shoes.

It's not much, and it's the only obvious trace of him in the bedroom.

So when Castiel looks at Sam, eyes searching, and just says "Jason," Dean just barely refrains from punching the cupboard.