A Behavior Tree developer creates, tests, and implements behavior trees, a tool used in AI programming to control the behavior of characters or systems. They design hierarchical structures that dictate decision-making processes, often for video game characters. These structures include nodes representing tasks, conditions, or decisions, which combine to form complex, dynamic behaviors. Developers must ensure the behavior tree functions correctly within the broader game or system, adapting responsively to various inputs. They also troubleshoot issues, optimize performance, and may work closely with designers to align character behaviors with overall creative vision.