Quick gift fic rec

 So I realize I've been terrible about updating about gifts I've received for various exchanges (sorry, pie_is_good; Gabrielle the Potential was a terrific idea!), but my Fic Corner gift's falling victim to the dreaded AO3 indexing issue, and I'd hate for it to get overlooked, because it's great:

Spaceman Spiff and the Redoubtable Scientist, by redsnake05.  Calvin (of Calvin and Hobbes) and Susie Derkins gen, but shippable without too much squinting if that's your thing.  Totally quick read, and tons of fun.