Many characters go through many incarnations throughout their time in comics. For Brother Eye, it's either been a source of good, or the embodient of evil and destruction.
Both times ironically enough, Brother Eye is a satellite that orbits either Earth or some other planet. It's design was to protect, many times to help stop alien threats. But, when it goes evil, it many times almost destorys the world. Whether its through an army of OMAC's, or literally creating zombie robot creations through its programming, it truly believes that all must serve Brother Eye.
In the recent comic series Future's End, Brother Eye took over the world, twice, in two different time periods, and it was us to multiple versions of Batman to stop them. The succeeded, and failed, and then succeeded again. But even still, the scars of Brother Eye are felt all over.