Janus

Janus was a Lantean who lived on Atlantis in the Pegasus Galaxy 10,000 years ago. He was among the few surviving Lanteans who returned to Earth after the war with the Wraith.

Biography
Janus was one of the most well-known and brilliant Lantean scientists, and his inventions were never orthodox advancements. He took great pride in creating out-of-the-ordinary technological marvels, most of which were either banned or frowned upon by the Lantean Council. He installed a time machine in one of the many gateships in Atlantis, and hid many of his controversial inventions and research (such as a component of the Attero device) in his secret laboratory. He also designed a personal cloaking device and made use of Intergalactic communication devices and Communication stones.

The first meeting Janus had with any people from our time was with Daniel Jackson, Janus had by this time begun experimenting in Time Travel and knew of the Atlantis Expedition, but not of Hoag's Object. It is hinted that Janus thinks it may be an alternate reality, but never confirmed.

He is at the Elyssia Shipyards when it it attacked and eventually destroyed by the Wraith, signalling the last possible line of defense the Lanteans have. He is very depressed at this point and contemplates going back in time to anihillate the Wraith, hense creating a paradox.

Daniel Jackson is able to convince him not to, and even more, to send him back to Hoag's Object using the recently rediscovere Time-Sphere.

When Major Sheppard and Dr. Zelenka were killed when a Wraith Dart destroyed the Time Jumper and crashed into Lantea's ocean, Janus was able to save Weir and became her advocate when she met with the Lantean Council. While he argued and defended Weir on her behalf that she should be allowed to return to her own timeline and prevent the Atlantis Expedition from falling into the same tragedy again, High Counselor Moros and Melia refused, and Moros angrily condemned his experiments, ordering the Timeship destroyed and the city to be evacuated.

Refusing to allow the future Atlantis Expedition to walk into the same disaster she herself had faced, Weir pleaded to Janus to help her find a solution that would save the expedition from walking into the same disaster she faced with herself. Janus remembered what Daniel had told him, agreed, and after doing some calculations, concluded that manually rotating the Zero Point Modules sequentially every 3,300 years would allow slightly more power to be available when the city was visited by the Atlantis Expedition and Weir decided to stay behind in the city to perform the task. Janus programed a stasis pod to re-awaken Weir every 3,000 years or so to allow her to manually turn the ZPM's. He also programmed a failsafe-mechanism into the city should power drop to to such a critical level that the shield would fail and cause the city, not to be flooded.

As Weir decided to stay behind, Janus himself decided to escape with the rest of the Lanteans to Earth with the hope that his efforts to save Atlantis for the future Atlantis Expedition would succeed, and was the last Lantean to leave Atlantis. Sometime after arriving on Earth he rebuilt his timeship, which would later be used to destroy a Goa'uld mothership and eventually retrieve a ZPM from Ra, which was later used to shield and save Atlantis from the Wraith attack.

Inventions

 * Attero device
 * Attero device control key
 * Failsafe-mechanism
 * Harmonic Resonance Light
 * Time-Jumper
 * Hand-held Time-Sphere