Although I think the distinction between rebel and revolutionary is cutting it too fine.
Depends on one's definition. For me, a revolutionary would be someone who is willing to destroy a social order with the intention to replace it with one of his own making. Of course a revolutionary can be lawful too (think Ayatollah Chomeini) and will rarely be chaotic, but successful revolutions tend to get out of hand very quickly, draw questionable people into its fold and hand out increasingly arbitrary sentences when the civil war drags on because in the long run, history has shown that it's oftentimes the more radical faction that turns out to be the winner (that's also the reason why I think you can't have truly committed CG "paladin of revolution"). A rebellion, on the other hand, doesn't necessarily have all that.
House Targaryen had a right to the throne by the rules of the day. House Stark and House Baratheon had pledged fealty to Targaryen. There is no clause in the vows that permits "and I get to argue/fight against the boss if he's batshit crazy and murders my entire family." It's exactly the kind of moral dilemma that Antigone faces. And, what makes it a dilemma is that there are obligations on both sides.
Of course there isn't such a clause, but I would argue there's no obligation that says "you have to put with everything the king does to your house because well screw you if you don't" - don't forget that the Targaryens started all this with Rhaegar abducting Lianna; and after Stark Sr. and son inquired what happened to their daughter/sister, they were executed in the most wanton and arbitrary way possible, by a king who pretty much raped law and custom himself because he thought this within his rights, thus legitimizing revolt. That's the difference to Antigone who had two conflicting but valid options by two legitimte sources of authority.
Further, I'm pretty sure whatever claim Robert had to the Iron Throne only springs into existence after you murder a bunch (what's the collective noun for dragons?) of Targaryens.
Of course, Robert's motivation was entirely different and more along the lines of "that albino fucker snatched away my GF, let's kill that bastard", but then again, no one says that Robert was a lawful character... Tywin (the guy who took care of half of the Tagaryen contenders) on the other hand clearly was, but a LE character would have other ways to handle things - Tywin also engineered, well, stuff *coughredweddingcough* which went totally against tradition but were considered necessary steps to secure royal authority without risking defeat.
But, I know for an empirical fact that many DMs would argue about all of this. It happened just a couple of weeks ago.
Oh, I believe you. The problem is also that many people seem to think that there's only one course of action for a specific alignment and only one way to play it, thus effectively limiting their player's choice. And saying that a paladin would be obliged to obey an evil overlord because otherwise that'd be chaotic... well, that's not just a sadistic "heads I win tails you lose"-choice from the DM, but also an extremely stupid one since it doesn't make much sense.
I made a contention, outside of a game, sort of along these lines. I was arguing that a Paladin was not slavishly obliged to uphold the rule of a terrible baron. But, that the difference between him and perhaps the Chaotic Good "solution" that another person was putting forward, namely sneaking and assassinating the baron, was that the Paladin would have to "call his banners" and meet the baron the field of battle. Alternatively, he could challenge him to a duel, trial by combat, etc.
This was treated as an extremely unviable option.
Well, I too would consider it an unviable option, but because it was impractical and not because it was out of character for a paladin
Funny that you take exactly this as an example, because it perfectly mirrors the course of events in Robert's Rebellion, and how LG measures alone can backfire:
- the LG Starks demand a trial by combat (=duel) and get shafted because Aerys doesn't play by the rules
- the remaining, equally LG Ned Stark forges a coalition and meets the Tagaryen loyalists on the field of battle
- the CG (at least back then, judging by the retrospective in his PoV characters) Jaime Lannister assassinates the king, thus preventing the death of half a million people, who would have bitten the dust if only the LG characters would have had their way.
- the LG Ned Stark wants to punish the CG/CN assassin Jaime Lannister by sending him to the wall because in his book, his act was utterly dishonorable although he helped his cause and (what he didn't know) prevented a catastrophe.
the Prussians who rebel against Hitler [...] seem like viable Lawful Good or Paladin-like characters.
Here I beg to differ. Prussian tradition can be summed up as "lawful neutral no matter the costs". This kind of obedience is already somewhat problematic in a society that's militarized by default, but gets truly out of hand once a totalitarian order takes its place. And don't forget that they were perfectly fine with following Hitler when he was still winning, and even though a number of them probably were out of the loop concerning the circumstances in the concentration camps, they knew that they were working for a definitely LE system that considered war crimes against the "right" targets a good thing and was out to enslave whole populations. A LN character could probably justify "just doing his duty" under these circumstances, and rein in any misbehaviour from his soldiers, but a LG character with a certain measure of information who isn't totally in denial regarding everything would have little choice but to refuse working for such a system.
The funny thing about LN people is that they're pretty much a joker in these scenarios like these because they can be found in all camps with little to no adjustment to their character.