Many people thought luck was an abstract concept similar to Fate or destiny. However, it is not the same. Although it is intangible and cannot be felt, luck can be felt and controlled with a certain power to a certain level.
As a seventh grade, King Leon knew the importance of luck and its potential danger. He knows if the twin girls want him dead, he will be over long ago. The only reason he is still surviving up till now is that the twin girls only want to test or 'play' with him.
Even though King Leon is cold and strict, he is open-minded about many things. As long as it didn't cross his bottom line, he could tolerate many things. In fact, if it is not to maintain his prestige as King and seventh grade, he may have a casual temperament.