Legonis is a member of the ruling Triumverate who seized control of the Decepticons after the (second) death of Straxus. He is arrogant, lazy, and believes in a rather complacent method of Decepticon rule on Cybertron. He tended to sit back and let the other two do most of the talking, making him probably the laziest of the lazies.
Marvel UK comics continuity
An unspecified amount of time after the (second) death of Straxus, a triumvirate of Decepticons, ingeniously calling themselves the Triumverate, came to power as the new rulers of Cybertron. Legonis, Octus and Seizer ruled together from their palace at the city Helex, sharing a three-seater throne. Legonis had the right seat (stage-left).
As rulers of Cybertron the Triumverate were too lazy for active aggression against the Autobots. Instead they spent their time enjoying arena fights between Autobot prisoners and powerful Decepticon warriors (such as Quake), even contemplating pitting Decepticon against Decepticon should they run out of prisoners, rather than going out to get more.
Legonis shoved Megatron into the area (of the arena), where cannon-boy bashed up a few Decepticons (including Quake, the schmuck) before making a speech about Decepticon values. Realising that they hated not going out and killing Autobots, the Decepticons turned on the Triumverate for being lazy bozos.
- Octus (Octavius), Legonis (Lepidus) and Seizer (Caesar) were a parody of (or perhaps tribute to) the ruling Triumvirate of Rome after the death of Julius Caesar.
- Legonis' robot mod doesn't have any obvious altmode cues. His arms and legs might be treads....