Human!Cas
The hunt went from good to bad to worse in a matter of seconds. The vampire nest was infested and right after you sliced one's head off, another came up from behind and cut down your arm. Cas killed it before it could feed off of you or turn you.
Cas helped you back to the impala and held you in his lap all the way back because of how bad you were shaking. You didn't notice Cas had got his chest sliced opened, so when everyone stumbled into The Bunker, his white button down was now matted to his chest from yours, his, and vampire blood.
"I'll patch up Sam, you go see if your boyfriend needs any help," Dean said.
You nodded your head and pulled Cas into your bathroom. "Cas, it's probably better to shower before I see if you need stitched up, so go ahead and hop in," you nodded at the shower.
He looked at the shower before looking back at you and slowly saying, "How do I actually use a shower?"
"You've never took a shower before?" Cas shook his head. "Strip down."
You turned on the water and let Cas change out of his dirty clothes. Cas stepped in and you undressed fast and got in a few seconds later. He was staring at the water, his back to you. You wrapped your arms around his waist and Cas blushed. "Should we be showering together?"
"A lot of couples do," you smiled. "Put your head under the water."
You watched Cas do as you said and he smiled. "Feels quite nice." He turned around and you gasped at the wound on his chest.
"Why didn't you tell me?" you asked, running your hand close the irritated skin.
"I am fine," Cas said, pressing a kiss to your forehead. "I had to make sure you were okay. You were scared when the hunt was over. How is your arm?"
"I'm fine, but you're not an angel anymore, Cas. You have to tell me if you get hurt," you said.
"I'm sorry," he whispered, lifting your chin up and pressing a soft kiss against your lips. "I will next time."
"Good," you whispered back.
Cas smiled. He grabbed a bottle from your shower rack and squinted at it. "How are all these chemicals supposed to clean my vessel? This makes no sense."
You laughed and grabbed it from him. "I'm not sure, Cas. I just know they work."
You showed Cas the difference between shampoo and conditioner and why different soaps are just all around better. Cas accidental emptied out half of your shaving cream all over the shower walls when trying to figure it out. In the end, you and Cas both smelled of strawberries.
"I like smelling like you," Cas said. You should him how to properly wrapped a towel around his waist so it wouldn't fall down and expose himself to the entire world. You sat on top of your bathroom counter, a towel wrapped you as well, finishing stitching up Cas. "Strawberry is a nice scent. We should shower together more."
"I'm glad you found it enjoyable," you giggled.
"Of course I did," Cas said. "I was with you."