T3-M4 was constructed by Janice Nall, a droid vendor on Taris, for the local crime lord Davik Kang. The droid was top-of-the-range for its time, and featured exceptional code-breaking and computer slicing skills, in addition to being able to mount armour and weapon upgrades. T3-M4's original purpose was to aid Canderous Ordo in breaking into a Sith military base on Taris for Davik Kang. Revan, under the advice of Canderous, assisted in stealing the launch codes from the base and the motley group manage to escape the planet without being vaporized by the Sith blockade forces.
When the Ebon Hawk, Davik's most appreciated light freighter, came into Revan's possession, T3 accompanied its crew for the rest of their journey, eventually being taken by Revan to the borders of the Unknown Regions.
T3-M4 resurfaced five years after the end of the Jedi Civil War. When the Ebon Hawk returned to known space with T3-M4, a non-operational HK-47, the Jedi Exile, and a former Jedi by the name of Kreia onboard. T3-M4 was instrumental in getting the heavily damaged Ebon Hawk to the Peragus mining facility while all the other crew members were incapacitated.
When the Exile awakened in the medical bay of the mining facility, T3-M4 helped the Exile gain access to the Peragus fuel depot before being found and disabled by the HK-50 droid and dumped in a fuel line, only to be discovered by the Exile and Atton Rand as they made their escape from the facility.
After the Jedi Exile and the others escaped from the Peragus system on the Ebon Hawk, they were forced to flee to Telos, where they were detained at Citadel Station. Atris had the impounded Ebon Hawk stolen from Citadel Station and moved to her Jedi academy in the polar region of Telos. T3-M4 was detained with the ship, and was thus also taken by Atris. At Atris's academy, his memory banks were downloaded by Atris's Handmaidens. The link between the academy's computer and T3-M4 worked both ways, however, and the droid was able to download a holorecording of the Exile's trial before the Jedi Council and a list of the locations of the remaining Jedi Masters.
When the Exile was captured on Nar Shaddaa by Exchange thugs in the employ of Goto, T3-M4 once again came to the rescue. The droid was "sold" to Vogga the Hutt and sent to work in his shipping warehouse. Goto had been intercepting all of Vogga's shipping by following his transport's transponder codes. The freighters would be captured by Goto's droid yacht, which was cloaked in orbit. To find and infiltrate the yacht, T3-M4 stole the transponder codes for one of Vogga's freighters and fought his way out of the warehouse when three HK-50 assassin droids tried to stop him. The Ebon Hawk's codes were then changed to match the freighter, and Goto's yacht intercepted the ship as planned, allowing for the rescue of the Exile and the destruction of the cloaked yacht.
During the Exile's journeys, T3-M4 was responsible for the Ebon Hawk's navigation, as he alone could access the navigation records of the ship due to a voice-printed lockout. Presumably, they had been locked by Revan to hide his destination. Eventually, after the destruction of the planet Malachor V—Revan's last known location—along with its Sith academy, the droid fulfilled his final mission by guiding the Ebon Hawk into the Unknown Regions. The Exile and T3-M4 left the explored space, and it is unknown what happened to them.
