I love Cato for a girl, for boy it's okay too, but I pronounce them differently per sex. The girls' Cato has the stress on the second syllable for me.
I like it paired with Dahlia, Guinevere, Lavender or Rosalind. I'd not use Jasper as a mn for a girl with a unisex first name. For boys I like Jasper, Reid, Victor, Zacharias and Zephyr.