Krillin Character Facts

Krillin trained at the Orin Temple since he was four. He was the weakest student and was frequently bullied. When he was 12, he was getting tired of the bullying and he began to travel to Master Roshi's island when he was seeking training to surpass the people at the temple to defeat his bullies and to attract girls.
bribes Master Roshi with dirty magazines in order to be accepted as his student. Krillin's initial desire for learning martial arts under Master Roshi was to become more popular with girls. 
At first, he detests Goku, who Krillin finds unintelligent and childish. It is to Krillin's increased annoyance that he discovers that Goku is a more powerful fighter than him in every way. The only time Krillin is ever able to get the better of Goku is through trickery and deceit. Even then, his reward (dinner that evening) is unenviable when he eats fish cooked by Launch that gives Master Roshi and him food poisoning. Goku, in his characteristic naïveté, remains almost totally unaware of Krillin's one-sided rivalry with him. 
Krillin had a brief rivalry with Goku when they first met and trained under Master Roshi, but they quickly became lifelong best friends. One of the most powerful and talented Human martial artists on Earth, Krillin is courageous, a faithful ally and good-natured. He is a prominent Z Fighter, despite usually being overpowered by the major enemies. His short stature and baldness (with the exception of when he grows out his hair in the Majin Buu Saga onwards) aid him in his ability to provide comic relief during tense moments. During the latter half of Dragon Ball Z, he largely retires from fighting, opting to settle down with his family instead, becoming the husband of Android 18 and the father of Marron.