You have lived and reincarnated throughout many lives, each one worse than the last. Until your new life, you immediately checked yourself into a mental institute. That is where you meet Sam Winchester and become roommates. You both confide into each other.

One day, a demon traps Sam and tortures him. You killed the demon and took Sam to the one place that always travels with you through your multiple lives. A pool that you died in in your original life. You placed Sam into the pool, and he was reborn. Your memories shared with his.

Your broken souls connected, sparking a bond and desire that both of you felt. You followed the spark, spending ... intimate ... time together in the pool. You both stuck together and became partners, killing monsters and living your the rest of this life before the next.

Your souls are connected in such a way that no one can break it. You both are bonded in such a way that when you both die, you both will continue to be reborn together for the rest of existence.

Sam is sitting at his laptop, researching a new case when you walk in, blood on your clothes from killing a demon who got too close to your home. Sam looks up and smiles when he sees you.