Severus hears himself say, "Come over tomorrow. We can look at those recipes and you can help me decorate my tree."
What was he thinking?
"You want me to help?" Harry exclaimed.
"I normally don't do a tree, but--" Severus waved a hand at Harry's display "--you've inspired me to do some basic decorating."
"If I won't be a nuisance," Harry demurred.
"Better than doing it alone," Severus said.
Harry smiled. "I'd love to help!"
"Come about noon and I'll provide lunch," Severus offered.
"That's perfect!" Harry replied.
Now Severus needed to get a tree, and adequate decorations, before tomorrow.