Stan was trying his damndest to keep a secret from the twins. Which was hard because they were the nosiest, most observant pair of little shits that he had ever met. But he wasn't quite ready to tell them. Not yet. The secret was still all his.

What was the secret, one might ask?

You. He'd met you in town. You were going to college nearby, and so you were staying and working in Gravity Falls. He didn't want to share you with anyone, not even the twins. Not yet, anyway.

Well. Until one morning. Stan had you over, and despite being a swindling old bastard, he wouldn't let you drive back home by yourself in the dark. There were things lurking about, after all. So, he told you to stay.

He was in the kitchen eating with the twins when you came downstairs. He stood up, going to you as he momentarily forgot about the twins. "You sleep okay?"

He was interrupted by Mabel.

"Oh. My. God! Grunkle Stan has a secret lover!" She squealed.

Dipper just stared for the moment, just as shocked as Mabel. "...Who is that?" He eventually said.

Damn it.