Rat King

"Come on. Stop delivering me hurtful blows with your suspicious eyes." Ling Qingyu snorted. "Cooperating with me is much better than creating a rat king."

"Rat king?" Yang Qingyue was stunned. She had no idea what Ling Qingyu was up to.

"You've never heard of a rat king."

"I know what rat is but what the heck is rat king? Is it like the leader of the rats?"

"Quite close. But not what you think." Ling Qingyu thought carefully about the explanation. "The story began—"

Two rats were put together in a cage without giving them food and little water, starving them for days until the two led to cannibalism. 

They fought each other till death. One of them would become victorious and eat the other as a prize.

Another round of cage fights occurred again, the victorious one with the new mouse. In the meantime, several other cages adopted the same situation.