Demon: the Fallen is a political game but the actual politics aren't always so easy to figure out. What does a demon want? Well, just about anything. How do they organise themselves? Well, into factions. And the factions organise by.... Erm? A lot of the actual politics behind the game need to be figured out through extrapolation and some heavy thinking.
Or maybe I was just dense and needed to really sit down and think on it.
Let's look at liege lords first as a major political consideration.
All Fallen Angels will have had *at least* one liege lord, probably more. Back in the day of the five legions, each Fallen had a superior officer all the way up to Lucifer. Before that point, each Fallen had to answer to somebody and that somebody was probably a Namaru (First House) though that wasn't so much feudal as bureaucratic so it might not have been as memorable or important to the Fallen, especially since their old boss might have been a loyalist. If your Fallen swapped between projects or legions, then they may have had more than one to whom they swore their unflinching loyalty.
Now your Fallen has returned to this world, they may have a few additional bosses whose needs they need to balance. These are your superiors in your House, Faction and Ministry (if you have one). None of them are going to want to compromise (more often than not), and all of them have their own duties to fulfil and their own needs to manage. Due to the dutiful and obedient core nature of even the most rebellious fallen, this can cause a lot of pain when they're lower in Torment due to conflicting duties.
And don't think that your initial liege lord is willing to be forgotten in all of this. Many Fallen adore their old lieges (or at least give them fealty) that they will sometimes even serve them when they're Earthbound due to a sense of duty and obligation. Since there is an expectation that old liege lords can call in favours from their vassals (and that vassals can call for protection from their liege lords), this system is also self-sustaining. Since everyone does it, and everyone expects to do it, you are going to cause a real stink if you ignore this obligation since it undermines the entire social structure that other, very important people, rely upon.
While your current superiors are expected to change occasionally, perhaps when you move cities or are re-allocated duties, your old liege lord may have been with you for a thousand years or so. You may have even served them while in the Abyss. This gives them a certain amount of power in how they deal with you. Most Tyrants would allow your old liege lord to speak with you, or for you, while you are imprisoned, and a valued vassal may also be accorded the same privileges if their liege were in prison. In fact, such a person might be granted access to you even when you wished to never see them again.
For those who have played Vampire: the Requiem, you could see within it a similar concept to the sire - childe relationship in the Invictus, only with more respect accorded to the ties and obligations inflicted upon the two of them. Only when your master remains in the Abyss can you safely ignore them and, even then, you may run into some serious trouble if they have other vassals who listen to them.
Luckily most liege lords and vassals are either happy enough to enjoy their lives independently or simply can't remember their old relationships. Often times, one or the other still remain in the Abyss.
Can you swear to a new liege lord?
I'd say so, though the old ties would still have some potency to them. It also wouldn't be as simple as being allocated to a new Fallen supervisor in your Faction, House, or Ministry. You'd need to evidence real commitment and devotion and there'd also likely be some ceremony as well. Demons, especially devils, should be really big into ceremony since they're primary resource (Faith) can be increased by it. They'd have a lot of traditions involving drawing as much Faith from their followers as possible and much of that pomp and ceremony likely continues to this day.
Anywho, those are my thoughts. How do you think the old liege lord - vassal system would work in today's Demon: the Fallen societies?