So I made it to the Nine Hells and had to reload a couple of times because Korgan / Edwin decided to say "Screw you guys, I'm going home"... What the actual fuck?

I can't believe that this hasn't been fixed in by the Unfinished Business and/or the official Fixpack considering how popular the game is.

Evil characters leave if your reputation goes above 18. Good characters leave the party if the reputation falls below 3. Whether this should be blocked in Nine Hells is controversial, especially for evil characters. I don't treat this as a bug.

I mean where are they going? It just doesn't make sense from a story perspective. It seems like an easy thing to fix and I can't believe it wasn't addressed.

From manual (page 38) :
REPUTATION EFFECTS ON PARTY MEMBERS Each party member has five different states determined by their alignment. These states are happy, neutral, unhappy, angry, and breaking point. Each of these states correspond to the four different verbal dialogue cues that a character has (that is, a character won’t complain if he or she is happy, but if the character is in an unhappy state, complaints will be heard).

You reached breaking point.

But the game is able to stop companion's personal quests timers when in certain chapters.

It should be able to block the break state when the story reaches certain points. Even the most evil of characters wouldn't want to ditch his party when stuck into the nine hells. They can't find the exit so it doesn't make any sense to leave.

There's a mod out there that removes the reputation break limit.

I say use some cheat to correct your reputation in the save before the problem.
Easier than a mod.

Well I managed to deal with it for most of the game by reloading saves, I have now finished the game.

I'm just pointing out that it really doesn't make sense story-wise to allow companions to leave at that point.

It should be an easy fix since in Throne of Bhaal companions can no longer leave the party no matter what.

Who cares about logic? Anyone who still cares about the game? Being overpowered doesn't defy logic as much as that.

Also there are plenty of legit arguments as to why an evil character would remain in a good aligned party. It's not like you have a ton of choice for companions either.

No matter how much the companion hates the party it doesn't make sense to ditch the group in such a place. They can't even escape without our help.

It actually kind of does make sense.

Edwin would totally go "Meh, screw you guys, I'm out", then sneak back aboard the planar sphere and let your bunch of rubes do all the work of getting everyone home. You're a bunch of goody-two-shoes (and this place sucks), so of course you're going to try and get home, and Edwin doesn't have to lift a finger to help you insufferable twits.

Iirc, Korgan likes killing things, and he doesn't have a lot of patience for those with a stick up their morals. The 9 Hells just have different things to kill, and hey, a little novelty once in a while doesn't hurt.

When I say the Nine Hells I meant the part at the endgame after you beat Irenicus the first time and get dragged down in hell.

But even for the Planar Sphere we need demon hearts to fuel the reactor so the companions still couldn't leave even if they ditched us.

By this point, any companions would be very confident in their abilities. If you become too insufferable, then they'll just strike out on their own and take their chances; doing dangerous, possibly suicidal, things is pretty much the job description of an adventurer, and all the Evil NPCs that might join you would see death as preferable to having to tolerate too much nonsense.

It isn't particularly important WHO finds and returns the fuel. They can stow away in the planar sphere and wait for you to do the work, and if you get yourself killed then they can try their hand at it. Either option means they don't have to put up with your attitude any more.

No amount of experience can possibly prepare a lone adventurer survive to the Nine Hells, let alone make them want to face it.

Why are you even trying to rationalize this? It doesn't make sense no matter how you look at it.

You should be aware of how reputation is handled in BG2 and how the canon route forces you into high rep. The game doesn't offer a legit neutral path.

The NWN HotU protagonist would disagree with it. :) In fact he managed there quite well.

None of the D&D computer adaptations offer a true neutral path because it's simply a mix of good and evil behavior. That's the meaning of balance in this system. In most games good characters are better rewarded than evil ones. BG2 offers at least options to easily lower reputation. The least intrusive to gameplay is morphing into Bhaal Spawn. There's also an option of killing someone innocent.