The Doctor was lonely. He had dropped off his best friends, The Ponds, after their latest adventure. He hated being lonely, it was worse than any other bad feeling. Or having your hat shot.
He knew who would like an adventure: River Song, his glamourus, flirty archeologist wife. He hadn't seen her in ages, not since they went to Asgard, at least. As if his old girl had read his mind, levers pulled themselves and buttons pushed themselves. The TARDIS landed, materializing around River. The Doctor stroked the console, and whispered a thank you.
"Hi, honey!" The Doctor grinned. River spun on her heel to face her husband.
"Hello, sweetie!" she Doctor's mouth opened and closed, rather like a goldfish "What's wrong?" she asked, a small frown forming on her delicate features. "But-you're-how...how?" He stammered.
"Pregnant, yes, you do know, don't you? We were only arguing about names-" Then it clicked. "Oh, great, younger version." she echoed The Doctor's words, which were her past and his future. The Doctor composed himself. "Okay, how, when and whose baby?" he asked.
"Well, when a Time Lord and a Time Lady love each other-"
"No! No, I know all that!"
"My due date is any day now, so this must have happened about 9 months ago."
"All in the future for me..."
"And it's yours. Well, they're yours."
"You're sure?!"
"Yes, I was there, the making and everything. I must say, that was the funnest part!" The Doctor blushed slightly. "Yeah, well... Anyway, you're sure?"
"Positive. Anyway, I should go, I have to meet a later version of you. Apparently you have a surprise for me."
"River, you can't leave now!"
"Sorry, sweetie." She kissed her husband for a good 5 minutes before pressing buttons on her Vortex Manipulator.
Then she was gone.