I was surprised to see no info on the inspiration of Sun in the trivia section... so, for anyone wondering, here it is.
Sun is very strongly based off of a character in an ancient Chinese allegory for enlightenment, called 'The Journey To The West'. This character, also named Sun Wu Kong, was a headstrong and mischievous stone monkey, who in his exploits became king of some (not stone) monkeys, got turned immortal 4 different ways, angered, beat in battle, and almost overthrew deities in most all of China's major religions, and helped a divine monk make it from one side of China to the other, get to the Buddha and back.
Similarities between Sun and Sun include:
acrobatics skills
strength
ability to make duplicates
fighting with a staff
being a monkey
names
mastery of martial arts
protectiveness of things they care about
regarless of outside joking demeanors, being good at heart
etc