Word Count: 405
Summary: No one knew Sheldon's birthday. [S08E16]
Disclaimer: I don't own The Big Bang Theory or the characters.
It has been their secret for a long time. Everyone thought it was a secret, and even Missy was prohibited from telling anyone – they did share a birthday, after all. Mary said nothing as well, and since no one had ever spoken to Georgie, he wasn't a loose end in the big secret.
But there was one other person that knew. One person that knew everything about Sheldon because he took care of him for too long.
It had been a long, hard day for Dr. Leonard Hofstadter. With a sick Sheldon to take care off, a deadline on a work project and having to assist Penny on her lines – more like line, but he was a good friend and was there with her – his day was terrible. Not a day to remember!
But it was on that day, late at night, that Leonard uncovered one of the greatest mysteries of Sheldon's life. His birthday.
It was in his wallet, on his ID. Maybe no one had ever thought of that, or maybe they did but decided not to do it.
But Leonard was curious, and needed some information to take Sheldon to the hospital – but it was just in case he needed to go. He took a glimpse at it and just nodded as if it was something he never understood. He now knew that Penny was wrong when she tried to guess his sign – it wasn't Pisces – and he also knew that he could never tell Sheldon he knew.
Sheldon found out about it a few days later because Leonard let it slip that he went to Sheldon's wallet. It wasn't hard for the tall genius to know what he also uncovered on his wallet.
"I'm sorry, Sheldon. I won't tell. But it's not that hard, you know? I mean, your birthday is on a bunch of cards of yours, it's on your employee's record..." Leonard stopped and looked to Sheldon that was just staring back at him.
"Very well. There is no way for me to delete that." He walked away after that, leaving Leonard alone in the living room, holding information only a handful of people – that were either Sheldon's family members or knew Missy – knew.
The next day there was a new clause on the roommate agreement that stipulated that Dr. Leonard Leakey Hofstadter could not tell Dr. Sheldon Lee Cooper's birthday to anyone.
The End
Just an idea I had while watching S08E16 when Penny said: "Not even Amy knows."
Leonard took/takes care of Sheldon even four seasons later, so there's (almost) no way that he didn't know. Here's my take on how he found out.