In his younger days, Lanius was a member of the Hidebark tribe, a group of Arizona natives trying to live in the nuclear wasteland. After the crushing defeat of Caesar's Legion at the first battle of Hoover Dam, the Hidebarks found themselves under attack, as the Legion began their old ways of attacking and absorbing tribes to bolster their numbers. Lanius was the champion of his tribes, and under his leadership he brought numerous Legion patrols and armies to their knees, and was strong enough to ambush squads and kill all of them. While Lanius continued to fight bravely, the leaders of the tribe realized that they could never hope to overcome the superior numbers of the Legion, and prepared a surrender. This betrayal filled Lanius with rage, and he murdered fifteen of his tribesmen, including their leader, before being knocked unconscious. When he woke, the Legion had already made the Hidebark the 67th tribe to fall before them, but Caesar personally appeared to offer Lanius a special position leading the Legion's forces in battle as he was impressed by the champion's fighting prowess. Donning a mask designed to resemble the Roman God, Mars, and wearing a full set of custom armor and his own unique blade, the Blade of the East, Lenius became the Legate and a powerful commander in the Legion- but with the promise that he could butcher the remnants of his tribe personally. He would later lead the Legion against 19 more tribes, conquering all of them without pause.
Fallout: New Vegas
With the Second Battle of Hoover Dam imminent, Legate Lanius arrived in the Mojave Wasteland to lead the troops against the New California Republic there. In three of the four possible paths- NCR, Mr. House and Wild Card, players will have to fight their way through the Legate's men to reach his camp. Arriving there, The Courier can either fight the Legate and his guards, use a speech check to convince the Legate to have a one-on-one duel and appeal to his sense of honor, or with a maxed out Speech skill or Barter skill, The Courier can convince Lanius to retreat from the battle entirely. During the battle with Lanius, he wields the Blade of the Eastt, a massive and unique sword that does huge amounts of damage. He also carries a couple incendiary grenades and healing powder. Once he is killed, only his helmet and sword can be looted from his body.
In the Legion path, The Courier begins to take their orders directly from Lanius as they near the end-game, and eventually help lead his troops to victory at the Dam. If the players decided to kill Caesar with his own Autodoc, then they will effectively be putting Lanius into power instead. Lanius would prove to be a far more violent leader than Caesar, and far less forgiving- rather than keeping Arcade Ganon on-hand as a doctor, Lanius has him crucified, along with the entire NCR Rangers, rather than the quick death that Caesar would have given them out of respect. He also exterminates the Followers of the Apocalypse and begins to hunt the remains of the Enclave. However, his more brutal leadership has no where near the influence of Caesar's, and the Legion begins to fall apart with him at its head.