Hmm, that's tough since while some of the things they care about confuses him, Kiba is still too indifferent toward most humans to be truly confused by them. I would say the way their general behavior goes against most basic survival instincts is his biggest question. Also, why they care about things they don't need. Kiba understands basic emotions but gets lost when they get more contradictory.

Demyx's take on de-aged Lea and Isa?