[Her reaction, hidden though it is, is familiar enough to him that he grimaces and shrugs casually, perhaps exaggerating his expression just for the show.]
Yeah, I know, it don't sound too impressive- but my folks decided it would be a good idea to call me James Buchanan, an' that's just too much of a mouthful and sounds like the name of some old office worker [or the least-well known President of the United States] so when I was 'round your age, I thought, hey, Bucky's a lot cooler, an' that's what I've gone by ever since.
[True story. And by the end of said story, he's again grinning.]
Magical things? You got it, Elsa. One scavenger hunt full o' magical things comin' right up! [He salutes her and gets up, wondering what they should start with. Maybe she should like the underground tunnels, or the bunnies, or the trains... or maybe he should find Merlin or Korra and ask them to show her what they can do.]