Disclaimer: I do not own Doctor Who and gain nothing from the creation of this story
The Doctor blinked in surprise and tilted his head as a child ran past them with a small toy spaceship. The only thing was that the ship was made up of hundreds of tiny plastic building blocks. Rose caught his stare and blinked, "It's just legos Doctor." Looking back to her the Doctor grinned before pulling on his glasses and walking over to watch a pair of little boys playing with their lego ships. Rose watched him with a smirk as he leaned over to watch carefully as one of the boys tried to fix his ship. Seeing that the boy wasn't having any luck, the Doctor knelt down, pulled on his glasses and started snapping the pieces into place.
Leaning against a light pole, Rose grinned as she watched the Doctor interact with the two boys. He'd be great with their own children in a few years. Finally, he stood and grinned at her as he rushed over and grabbed her hand. The Doctor pulled her down the street, making Rose shout, "What are you on about?" Grinning at her over his shoulder the Doctor yelled back,
"The nearest toy shop closes in less than an hour."
"You can build worlds with these," the Doctor muttered softly, his gaze focused on the tiny building blocks in his hands. "Such a simple and primitive toy on Earth, but these Legos have great potential." He snapped two black blocks together and carefully snapped them onto the side of large round disk made of the same blocks. Grinning, he adjusted the glasses on the tips of his nose and pulled the large disk into his lap. Carefully he added a few more pieces and softly continued, "I've seen the future of humanity and these well never vanish. New Earth and children are still learning how to put two and two together with legos." He rubbed his hands together with glee, barely containing the grin on his face, "Yes, a toy to you, but a vast possibility to me. They've made all kinds of sets: western, space, medieval, Harry Potter-"
Rose's laugh made him look up in surprise at the doorway. She was leaning against the doorframe in her dressing gown with a grin on her face. Holding back another laugh, she raised her eyebrow and looked at the Doctor. He was sitting in a vast sea of legos on the floor of their children's playroom. The doctor blinked up at her with surprise and Rose stood up and crossed her arms, "You are aware that Alex and Abby went to sleep an hour ago." He looked down at the legos in his hands and looked around the room in confusion. Turning back to Rose, he grinned and snapped another piece into place,
"I love these things."