Fifteen years ago, Rudy and Ty both studied under the Grandmaster. During the final battle to decide who would be the Grandmater's official apprentice, Ty was distracted during the match and Rudy suscessfully won the fight. Much later, Rudy was a top amateur martial artist but was sidelined by an injury and lost his fire to compete. After hitting rock bottom, Rudy took his entire life savings and bought the Bobby Wasabi Martial Arts Academy in The Bay View Mall.
Rudy can be wacky and gross at times, and is often more than a little childish. He often obsesses over childish things, like being willing to spend four thousand dollars to build a model trainset, purely to win a thousand dollars. Despite this, he has a mature and responsible side that he shows when needed. Although a highly capable fighter in his own right, Rudy will often try and solve disagreements with words and will willingly back down if he's in the wrong. He normally only gets into fights if he's attacked or left with no other opportunity, though he has lost his temper before and used Karate outside of the dojo for petty revenge. (He later apologized and taught Jack a valuable lesson about not fighting.) Rudy has shown to be somewhat sensitive about his height. He is also very charming and often portrayed as a ladies' man, though he is currently in a relationship with Seaford High's Health teacher Bethany Applebaum. He is also determined, brave, and loyal, never abadoning a friend and carrying on even if it looks bleak. In Season 3 Rudy agreeds to adopt Sam, a young boy who Grandmaster is trying to get adopted, to whom Rudy becomes a Father/Older Brother to.
Rudy is a third degree black belt and is, thus, incredibly skilled at Karate. His skills are demonstrated on many occasions, and much like Jack he is able to take on multiple opponets as shown in "Dude, Where's my Sword", "Swords and Magic", "Wedding Crashers", etc. He defeated his archenemy, the Black Dragons' Sensei Ty in "Clash of the Titans" and even a professional wrestler in "Rowdy Rudy". He is also one of the only characters who has beaten Jack in "Sensei and Sensibility".
In Badge of Honor it was revealed Rudy has two pets; a cat named Tip-Tip and an unnamed dog.