Yang Yu lowered his head and thought for a long time before he hesitantly gave his answer:
"Is there some kind of invisible drive that compels them to fight each other?"
"A rather vague answer. Not exactly right, but not wrong either," Owen smiled. "There is indeed some kind of force driving them to battle one another. You could simply understand it as a desire for them to become stronger.
By killing an evenly matched or stronger opponent, they can become stronger themselves, so they do exactly that.
It's similar to how, among humans, some people continually challenge opponents stronger than themselves to grow stronger.
Magic Beasts are different from ordinary creatures, after all.
What might be a fatal wound for an ordinary creature could only be a minor injury to a Magic Beast. A wound that would take ordinary creatures several months to heal might only take several days for a Magic Beast.
