(See http://www.reddit.com/r/leagueoflege...lities/c53l5cf for rough translation from chinese leak, CCed here)
Jayce is a scientist of Piltover. His hammer resemble courage and his shield resembled wisdom. His attractive personality and inventions increased the quality of living in Piltover. However, his inventions attract also his enemies,one of them Viktor. Viktor launch a strike at his laboratory and stole a blueprint of a transformative weapon. Jayce believing that Viktor will use the blueprint for destruction purposes, he appeals to the piltover government to launch a counterattack but piltover gov refuses. So he basically equip himself and attack viktor's base, getting the blueprint back and forcing viktor to retreat.
however, jayce knows that he already became the centre of attention to his enemies. he received a hero's welcome back in piltover and he decideds to protect piltover from future enemies.
quote: " If we are vigilante, Piltover can face any enemies. I am a living example"