Bribery

Daughter, arriving at 2am: "Mom, I'm cold."
Daughter in my bed at 3am: "T-e-n spells ten! Hey! Mom! I can spell ten!"
Daughter in my bed at 4am: sits bolt upright, an announces in manner of eureka: "Hey! I can draw fruit!!"
Finally made warm milk for daughter, which worked.
Son, arriving at 6am: "Mom. I'm bored to death."

And this is why they are having a sleepover at grandma's tonight.