How many legions are left and what is the status of them?

[ObsidianFire]

Lore Book 2 goes somewhat into the XIVth Legions' situation. Which is both isn't and is as bad as you think it is. Castrum Meridianum outputs enough refined ceruleum that the entire Legion wasn't dependent on Garlemald for ceruleum when Gaius split them off from the Empire. So they can pretty much operate as much magitek as they want and who knows what else (they've got an entire shard of Dalamud to research, so... who knows what they could find down there). As late as 2.5 (when the Keeper of the Lake dungeon launched), the XIVth Legion was still cut off from Garlemald. The reason they were in the Agrius in the first place was because they were so starved of materials, they were striping parts from the 15-year-old wreck.

As far as Eline Roaille goes... she was getting desperate and wanted out of Eorzea. And we know she wasn't thinking as cleverly as usual because she was making a lot of mistakes which clued us into who exactly she was. The XIVth Legion meanwhile, was still cut off from Garlemald. Getting one of the Emperors top spies would probably have given them some much needed info on what Garlemald itself was planning on doing.

For Emerald Weapon, we learn that Rex called ahead and told everyone in Castrum Marinum that if they left before he got there, he wouldn't go after them. And those are... basically his dad's subordinates and Rex himself used to be in the XIVth Legion. There's no way the XIVth Legion in Castrum Marinum didn't know who Rex was... and Rex was planning on turning over the castrum to Gaius anyway once he won. The situation is less the XIVth Legion wanting to work with the Empire and more them knowing that no matter how it ended, they'd probably get their castrum back anyway. If Rex won, Gaius would get it, if Rex lost... Eorzea has been leaving the castrums alone for a reason; they don't have enough people to both fight a way against Garlemald in Gyr Abania and kick the XIVth Legion out. And as far as we know, the XIVth Legion hasn't been bothering anyone in Eorzea since... the 2.x patches as long as no one bothers their castrums... which is... more or less where they live.

It's also worth mentioning that the XIVth Legion has only been Gaius' legion. He's the one who started it and has always been the Legatus of it, and presumably it was being run closer to his own philosophies than other legatai's (Wyrlet quests seem to confirm this anyway). It's... probably not the worst legion to find yourself in compared to... a lot of the other legions we see. I can see the people in the XIVth Legion deciding, all things considered, they have a pretty sweet deal being stuck in Eorzea given they've managed to sit out two whole civil wars and the Gyr Abania conflict and haven't doing anything really... questionable... ever since 2.x. Seriously, they had the perfect opportunity to show they were loyal to the Empire in Stormblood as they are in Eorzea's backyard while all the Grand Companies were away in Gyr Abania and the XIVth Legion did... absolutely nothing. And they're still doing nothing except not causing Rex, Gaius and the WoL problems when Rex chooses to make Castrum Marinum the place for the showdown. Which... would have been another good opportunity for the XIVth Legion so show that they're loyal to the Empire and not... whatever (or whoever) they are actually loyal to.

At the very least, the XIVth Legion aren't being stupid about getting on the bad side of the people who are running the countries they are... essentially in exile in. There's native Eorzean groups that are causing more active problems than the XIVth Legion is, so... props to them for at least staying out of the way?

The VIth Legion is in a similar state, but we do know they are loyal to the Empire still and are sending information about Azys Lla back to it. They are just... stuck there though... They haven't gone AWOL like Gaius did with the XIVth Legion.