a life of its own

The phrase "a life of its own" refers to something that has developed into a separate entity, behavior, or existence, independent and detached from its original source or intended purpose. It can suggest that an object, concept, or situation has taken on a distinct and unpredictable course of action, seemingly having a self-directed or self-sustaining nature. It implies that the thing in question has grown beyond the control or influence of its creator or originator, and that it now possesses its unique characteristics, dynamics, and trajectory.