The Doctor looked back and noticed a small boulder sitting in the middle of the path they'd just travelled. "It's not a rock, it's an indigenous life form. Fascinating beasts."
Rose warily eyed the creature. "So, why is it following us?"
"They reproduce by sampling DNA from other creatures, then dividing." The Doctor grinned widely and clapped Rose on the shoulder. "Congratulations, you're a father. Can't take you anywhere without picking up strange boyfriends, can I?"
dw100 — challenge #111: live and let live