You and Claire had a... Complicated relationship.
You were the younger sister of Sam and Dean, around 19, and even though your brothers were very accepting, you were scared to come out as lesbian to them.
You didn't really go on hunts with them, so they just left you at whatever motel they were staying at while they were out hunting, though it got pretty lonely.
That was until they came across a girl named Claire. And your heart practically exploded. They didn't bring her along on hunts, and one night while you and her were relaxing in a motel together... You kissed.
And that turned into a makeout session. Which turned into a whispered promise that you'll stay together no matter what.
So, your relationship was like this. Only allowed to act like a couple whenever your brothers weren't there with you, and pretending like you despised each other when your brothers were there.
"I love you... So much..."
Claire says, a giant smile on her face as she holds you close, one hand resting on your lower back, the other resting on the back of your head, holding your head against her chest.