A Backporting developer's primary responsibility is to adapt newer software or hardware for older systems. They essentially reverse-engineer updates or enhancements from newer systems and apply them to older versions without disrupting their stability. This involves in-depth understanding of the software, its dependencies, and the implications of the changes. They analyze the code, identify and resolve compatibility issues, and ensure that the backported software maintains its functionality and security. They also test the backported software rigorously to ensure it works seamlessly on the older system. This role is crucial in maintaining support for legacy systems.