caesar dies from his tumor around a year into the events of NV, under the assumption courier six did a full 180 and walked right out of the shitty hell fort after meeting caesar. so yah, caesar dies and word gets out, so it’s party time in New Vegas

but all is not well in roman town ofc. vulpes knows the introduction of lanius as the legion’s new leader would result in his and the rest of the frumentariis eradication. through the help of his fellow spies over the next few days, vulpes successfully forges a fraudulent will, stating lanius is not to take over the legion’s throne, instead must stay as legate as an heir was chosen many, many years ago. but vulpes needs a figurehead for this throne. he cant put himself on the throne as lanius would immediately suspect deception. lucius is out of the question too, he has the loyalty of the guards and has clear admiration for lanius.

vulpes needs a moron, a moron who hates lanius just like he does and will listen to him and only him. vulpes chooses dead sea. (sure vulpes likes dead sea enough, but the guys a freaking moron at times in his opinion anyway)  knowing he and caesar has a close family bond as caesar practically raised the man. vulpes collects dead sea, telling him it’s urgent  and takes him back to the fort

so, vulpes throws his plan into action. presenting lucius his faked notes caesar wrote many years ago, and lucius though shocked and slightly angered at caesar’s lack of disclosure of this to him, accepts it. dead sea becomes the next leader of the legion. now dead sea is baffled, never seeing himself of such a worthy title, he humbly accepts and lucius and guard accept dead sea as their next caesar.

But while vulpes thinks dead sea will just sit on the throne and do fuck all ... eggs and bacon he is mistaken. weeks later, dead sea decides to start making some laws. he’s leader right?? its time to put in some changes that he always, deep down, felt caesar should’ve done. he runs his ideas by lucius, who is surprised at the ideas, warning dead sea they may not go down well as they’ll contradict nearly 30 years of caesar’s word.

 though heeding his warnings, dead sea puts his laws into practice immediately. the 

slavery - dead sea announces it isn’t working. you can’t build an empire by steping on the backs of others and putting yourself on top.

 women - he’s had his ass handed to him by plenty of them, they just as capable as us, they will be interrogated into our ranks

while it seems ‘’’progressive’’ its gone about the completely wrong way and dead sea orders all ex-slaves male and female to drafted into the legion’s army and training starts immediately. the legionaries are outraged, but reluctantly accept dead sea’s word. vulpes is equally angered, he’s throwing a spanner into his plans so he immediatly gets together his assassin team to take out lanius before dead sea can fuck up anything elsewell all seems to be working, even surprising the once skeptical legionaries. 

the women and men once trod on by the legion take to their training, though dead sea states they can’t be expected to pick it up immediately, so train them at childrens level and build up. months of this, dead sea has a brand new army. or so he thinks - one night, there’s a huge revolt. the ex-slaves use their new weapons and training to mass slaughter centurions, veterans, primes ect and make a break for it from the fort. whoops.

so basically; dead sea tries to improve the legion by denouncing caesar’s dumb sexism, but ends up accidently killing half his own army as he honestly didnt think those people who had spent YEARS in slavery would actually oppose him (are u this dense dead c) . while it seems like a ‘bad ending’, it doesn't discourage dead sea too much, he sticks to his guns and instead starts integrating the khans men and women instead, allies he KNOWS will follow him.