Charlie and Dean are best friends, practically inseparable since the day they met. When Charlie suggests that they should create a "No kiss list" of people neither of the are allowed to kiss to avoid future awkwardness and heartache after Dean kisses Charlie's ex girlfriend on New Years Eve, Dean agrees. And the list works fine... That is until Charlie has to tutor Jo Harvelle, Dean's ex girlfriend (notorious number 2 on Charlie's no kiss list) and slowly starts to develop a crush on Jo. That is until Dean kisses Castiel, Charlie's awkward and socially inept yet adorable brother-in-law which results in every brick of the foundation cemented to ensure and strengthen their inseparable relationship starts to crumble as they try to sort out their closeted feelings.