A/N: Hi everyone. This is a prompt from Anonymous on tumblr requesting a story where Sheldon works from home and involuntarily makes his baby boy laugh his little heart out. I hope you enjoy!

Sheldon kissed his wife goodbye as she walked out the door on her way to work. When Amy's maternity leave ended, Sheldon volunteered to work from home to care for their infant son, as he wasn't keen on leaving him at a germ-infested daycare center. Normally the little boy slept most of the day, leaving Sheldon plenty of time to formulate equations on the multiple whiteboards set up around their home office. This was not one of those days.

An hour of silence went by before he heard Stephen fussing through the baby monitor. After feeding and changing him, he set the little boy back in his crib and headed back to his work. Just as he picked up his marker, the sound of crying crackled over the monitor again. Stephen was usually a quiet baby, so Sheldon was concerned. He picked up his son and assessed his temperature, skin tone, and pupils. He didn't appear sick. Perhaps he was just tired but couldn't fall back asleep. He held him to his chest and rocked him gently. Stephen's big blue eyes stared up at him, and his sobbing subsided. When the baby's eyelids fluttered closed, Sheldon placed him back in the crib and quietly padded out of the room.

Once again, Sheldon picked up his marker and set to work, but within minutes, muffled crying alerted him that his son was calling for him. He set the marker down and sighed. He was never going to get anything accomplished today. Sitting in the nursery room rocking chair with Stephen on his lap, he told him the story of The Little Engine that Could. The little boy hung on his every word. When he reached the end of the story, he kissed the top of his head and inhaled his intoxicating baby scent. For the third time, he lay the baby in his crib, but before he could even take a step toward the door, Stephen sobbed again, his little hands trying to reach for his daddy through the slats.

"I can't stay in here with you all day," Sheldon murmured. Then he had an idea. Maybe he could bring Stephen into the office. "Daddy will be right back."

After moving some whiteboards and pushing the furniture out of the way, he assembled the portable playpen in the corner of the room and fetched his son. Sheldon watched as the little boy took in his surroundings. Though Stephen was only four months old, he decided to use this as a teaching moment.

"This symbol here," he tapped at the whiteboard with his marker, "is called a cathode. It indicates a negative electrode in an electrolytic cell. This one with a squiggly top is called pi. Pi is a mathematical constant with an infinite number of digits in its decimal representation. One day I will teach you the first 1000 digits..."

Stephen watched the marker's path as it flowed from one symbol to another, similar to how a cat's eyes follow a laser pointer. When Sheldon walked over to the next whiteboard, he tripped over a fallen marker and fell flat on his butt. Stephen squealed with delight.

Dazed, Sheldon looked at his son at eye level through the mesh wall of the playpen. "You think it's funny that Daddy fell?"

Stephen giggled uncontrollably. His laugh was infectious, and soon Sheldon joined in, chuckling at himself.

"At least you're not crying anymore; laughing I can deal with." He stood and dusted himself off then reached down to ruffle his son's hair.

When Amy returned several hours later, she peeked into the office to find her husband chattering away, explaining every step of his formula to their son. She smiled softly, unsure if she should make her presence known or allow them a few more minutes to bond. As if sensing her presence, Sheldon turned to the doorway grinning from ear to ear.

"Did you have a good day?" He asked.

She walked over to him and kissed him gently. "Pretty good. It looks like you two have been enjoying each other's company."

"Oh, we have. Staying at home was the right decision for me. I get to spend time with our son and still get my work done. It's a much better arrangement than being at the university because I don't have to deal with the likes of Kripke."

Amy plucked her son out of the playpen and held him close. "I missed you so much, but I'm happy you spent the day with your daddy. Did you have fun watching him?"

Sheldon wrapped his arm around his wife's waist and kissed the top of her head. "I know he did because he didn't cry the whole time he was in this room. He fussed the entire time we were apart, so I brought him here and kept him entertained," he told her truthfully. What he didn't mention was his mishap with the marker. That secret would stay safe between him and their son.