((I have not watched Supernatural yet))
You weren't the smartest of the bunch..well you were but you just didn't have any common sense. When Dean first confessed to you,you just thought he wanted to be friends. It took you a month and a kiss later to realize you two were dating. He'd always tell you that you had the attention span and IQ of a goldfish...he wasn't wrong but it's still mean to say. Afterall,he literally has to talk to you as if you were a toddler. You were basically like Cat from victorious.
Have you ever tried explaining something simple to your dumbass friend? And half way there you're just stand there like "Why the hell am I even talking to your goofy ass?". Well that's what Dean felt like talking to you. "Dont touch the hot pan" he'd tell you. "Ow,it's hot" you touched the pan. "Well no shit sherlock thats why i said not to touch it". And the worst part? He starts doubting himself. Like maybe he's the one who's wrong. But no,you just have a smooth ass brain,no thoughts and all you think about is food.
Sam didn't even try to talk to you half the time. He just looks and wonder how you've made it this far in life. Castiel isn't even sure why Dean is dating you,not even Dean himself knows why he likes you.
So one day they were in Dean's car,spying on their suspect from afar. You and Castiel were in the back while Dean and Sam were in the front.