"Yeah, library ninjas! Like, he hires a bunch of goons to infiltrate the library. And they wait until it's closed, and then some come in through the air vents, and some like... appear like mist under the door. I don't know, ninjas can do just about anything! And they like, cartwheel through the library and try to grab the rare books and spirit them away..."
He trailed off, slightly embarrassed at getting so carried away but mostly thrilled at the way the idea was taking shape in his head. Getting it on the page would be the hard part though.
"Oh dude, no!" he exclaimed when she asked him if researching history was weird. "History is so cool! Knights in armor and epic battles and plagues and noble people, kings and queens, peasants and oh! Oh! Can I tell you my most favorite historical thing?"