With Will's divorce, JJ hadn't dated much. Her job and kids didn't let it work until you came into the picture. You were new to the team, and with the regulations, it just couldn't happen. It was against what the BAU was, it hurt honestly. She pined after you, and you pined after her. Eventually, with a girl's night, Emily and Garcia had gotten JJ to get over the regulations and go for it. They would be the only ones who knew. Strictly. No, Hotch. No, Spencer. No, Rossi or Derek. They would have your head.
After a while, the boys eventually found out and didn't care. JJ didn't know they knew, and neither did you. It would have been better for the team if no one had talked about it. So they didn't. You and her, always forever.
"Why is this so calming?" JJ asked when you were over for dinner one day. You raised an eyebrow, what did she mean by that? She felt the need to clarify. "I mean, us. The team doesn't know besides Emily and Penelope. It feels so.. refreshing. They're always in our business, it's nice we can keep this to ourselves. Y'know?