From PopStar! Magazine:

     On the show, Leo is characterized by his natural curiosity.  And it's only natural that you'd be curious to learn more about Danny Slavin, the great-looking guy who plays him!  Danny was born and raised in Phoenix, AZ, where he trained for years in the martial art of Kuk Sool Won.  That's where this cute dude gets his cool moves for the show.  You probably recognize him from his previous gig on Saved By the Bell.

From Danny:

     Back when they were still filming the show, Danny used to hang out with his co-stars, Archie Kao (Kai) and Reggie Rolle (Damon)!