Another close call between badger and lion, and Hufflepuff only won out when I started to try and explain why he wasn't one. Cal seems like he'd be in Gryffindor, since he's recklessly brave, he's a thrill seeker, he loves adventure -- but I think his heart is with Hufflepuff, in that when you get past character traits and into core values, Cal prioritizes loyalty, trust, tolerance, and friendship. I think he's one of those party-hard Hufflepuffs who's intensely popular and friends with everyone ... he's like Cedric Diggory.
He comes off as lazy and unmotivated sometimes, but this is the guy who'll drop anything to help you move your couch, or fix something around your house just to be nice. He strongly values fair play and kindness, and those things take precedence over his adventurous side; I think he's more gentle than people really see. He tends to give people the benefit of the doubt, he can be overly trusting because he thinks everyone's going to be as kind as he is -- and he remembers and holds grudges if you break his trust.
The Scarf of Sexual Preference says: Not Remotely Bi-Curious.