every once in a while dean wakes up in the middle of the night and goes to the kitchen for a glass of water and he hears cas laugh in the library so he goes there and cas is sitting at the table watching funny cat videos on his phone with books scattered all across the table and dean falls a little more in love with him every time and he makes cas some tea with honey and gives it to him with a soft smile before either going back to bed or getting a blanket and sitting next to him. sometimes he ("accidentally") falls asleep with his head on cas's shoulder

dean finds his cat killing a mouse and because he sees the cat as his own baby child, his instincts to Protect From The Hunter's Life instantly flare up and he's now crouching next to his cat giving him an extremely serious lecture on how once you start killing, it's hard to stop and it does no good, especially for someone so young. you've got a chance now cat, get out of this life while you still can. you deserve better things than this, hell, you are better than this. don't waste your nine lives like the rest of us hunters, senselessly killing things for a job, losing sight of what’s right, it's not worth it. i love you, cat, you're strong enough to leave now, i’ll help you to do it, i just know you can. and sam, who set the cat on the mouse because the bunker has a mouse problem, rounds the corner to witness this and realises his idea maybe wasn't the best ever 

to me, miracle the cat also makes a lot more sense for dean because I can fully see dean developing a fear of dogs after getting mauled by hellhounds and just. never recovering from it. like he thinks it goes away for a while but then a dog will bark loudly and dean winchester who has fought the devil and killed death will jump 3ft in the air