Hello, per the title I need some help figuring out where my character goes from here.

essentially, after reading an inscription on a goblet my LG devotion paladin of ilmater was alignment changed to LE but everything else is the same. I didn’t take it well and the key criticism from my fellow players was that I was making my guy act like a jerk, but this was mostly coming from the fact I had to rp a new personality for my guy on the fly. How am I supposed to play this? I do NOT enjoy playing evil characters. the dm has stated however thst if I keep my attention perked and my options open there ways in the underdark dungeon we’re in i can get back to normal or rp my coming back to the true light thanks to my friend the party bard. In the meantime I’m going to give playing this heel turn character arc a genuine try ala black simbiote suit Spider-Man WITHOUT going far enough to break any major tenants of ilmater. Thoughts and advice on how to interestingly proceed are greatly appreciated.  

Honestly, I don’t see how it’s possible.  Your subclass could be kept the same, but Ilmater - being a solid Neutral Good deity - would almost certainly reject you.  I suppose the caveat is that your alignment change was magical and not made by choice.  However the counter argument to that is that a vampire is always brought back as evil and they have to redeem age themselves to a different deity than they served or worshipped in life.  If the DM is saying that you can still serve Ilmater while Lawful Evil, I have no answer to that.

As far as the limited impact that alignment has on roleplaying, I’d think of it thus: Evil or Good is how much you care about the lives of others, and their safety.  Evil obviously views everyone but themselves as expendable, and even prey for suffering.  Lawful and Chaotic is whether you are concerned with how well you fit into society and conformation to.  Chaotic is only concerned about themselves, and doesn’t care about any rules at all.  So a Lawful Evil character like yourself would initially start out generally following the “rules” of the party, being concerned about their positioning, while being utterly indifferent to any pains or deaths suffered by those same party members.  Not to say they wouldn’t see about healing or even raising for the dead fallen allies but only so long as they were useful.  I also feel they’d start to eventually push for new rules that better reflected their own moral alignment, and looking for loopholes or other exploits to the rules that already existed.

You are making a common D&D mistake - Evil on the alignment chart does not mean you are villain, a heel, or an antagonist.  A protagonist can be Evil-aligned relatively easily—I have DMed for parties where the clearly Evil character was the main impetus for saving the world. 

An evil character is one who is willing to use whatever methods they want to accomplish a goal they are personally interested in. Use that as the basis for building your character—not “I am a bad guy now.”  The former creates a real, interesting, and dynamic character, whereas the latter creates an uninspired cliché.

So, start with your character’s old personality. What were the things he liked, and how would he go about getting those things if he felt fewer restrictions on how he should act?  You painted him as a divine man, use that—twist his belief in his god to something still very much aligned with his old goals, but through a slightly different lens.

Ilmater is the god of suffering—and is a god who willingly sacrificed himself to suffering to take away the pain of others.  Build on that.  Your character used to derive meaning from ending folks’ suffering (presumably based on the god you picked).  Your Evil Paladin can still want to end others’ suffering; he just is no longer under the illusion he is doing it purely altruistically, but because he selfishly craves the adoration of the folks he rescues.

And he can still very much be about transferring suffering away from those who needlessly suffer. He could be willing to inflict that suffering on the tormentors, using any methods, regardless of morality, to carry out an eye for an eye punishment.  You can even mix some of the selfishness and willingness to sacrifice self, corrupting a former willingness toward self-sacrifice into self-flagellation. 

Taken together, you would have a character who actively is helping people (albeit because he wants the glory it brings or because of some other internal motivating factor) and actively punishing the wicked.  Everything he does could be for “the greater good”—he is just doing so in a decidedly less than savoury way.

Overall, remember - your character is still the same person, with the same beliefs, the same desires, the same experiences.  The only thing they are changing is how they act in furtherance of those beliefs and desires.

You will come up with a much better character if you keep 95% of your current character, and use this opportunity to explore the “what if a critical 5% was different?” question presented by this scenario.

I'd say: Make it clear to the GM that you're not having any. Inform him or her that your character is - obviously - aware of this shift in perceptions, and dislikes the new person they've become. And that they're going into therapy (or cloistered meditation, or whatever) until they can reestablish their moral foundations, and then roll a new character. Make it a LG paladin of Ilmater for good measure. 

The GM does not get to change characters - other than by the reduction of hitpoints.

Quote from Acromos >>

I'd say: Make it clear to the GM that you're not having any. Inform him or her that your character is - obviously - aware of this shift in perceptions, and dislikes the new person they've become. And that they're going into therapy (or cloistered meditation, or whatever) until they can reestablish their moral foundations, and then roll a new character. Make it a LG paladin of Ilmater for good measure. 

The GM does not get to change characters - other than by the reduction of hitpoints.

 
This is not great advice, and really should not be given much weight. 

Magic is real in D&D. Curses are real in D&D. And curses which fundamentally shift an alignment have been and remain a part of D&D since the game’s inception. Telling your DM to “sod off” for doing something that is a fixture of this game is not a good look.  Furthermore, it is tantamount to admitting “I am not capable of rising to this challenge, and would rather throw a fit and refuse to play a fundamental part of this game than potentially explore a new and unique challenge for both my character and my player.”

Fortunately, I think OP already knows this. While OP is frustrated about the alignment change, OP is not asking “how do I undo this?” or “what should I say to my DM to get them to change their mind.”  OP is asking “how do I actually play this”, making the answer of “refuse to play it” both unresponsive and unhelpful. 

I say all of the above for OP’s benefit. Yes, you are frustrated, but there are ways to use this to both align with your preferred playstyle, a (somewhat corrupted) version of the character you already played, and with your party.  I do not want the above user to cause you to second guess yourself—you got this, you can very likely get through this with some creativity, and you might discover something new about your character and your own playstyle in the process. And, who knows, you might hate it the entire time, until your curse is lifted.

But you won’t get to know if you enjoy or hate it if you just shut down and refuse to engage in a fundamental aspect of the game. 

Gotcha 

My friend tried to get me to understand this concept by using other characters like peacemaker as examples but the way you broke it down here really clicked in my brain the way other explanation ms failed to. 

this was a big help, thanks!

Quote from MECHA_PHANT0M >>

My friend tried to get me to understand this concept by using other characters like peacemaker as examples but the way you broke it down here really clicked in my brain the way other explanation ms failed to. 

this was a big help, thanks!

 
Happy to help - good luck with your character’s journey!

Speak to your DM about the fact  you don't take it well and do not enjoy playing evil characters. While your alignment might have to change, no one should force you to do anything you're not comfortable with.  

Alignment changes often poses challenges but it's up to the player to make it as much or as little impactful as they want Alignment broadly describes moral and personal attitudes and is a combination of two factors: one identifies morality (good, evil, or neutral), and the other describes attitudes toward society and order (lawful, chaotic, or neutral), which for you didn't change as you're still lawful. 

The summary of lawful evil describe the typical behavior of a creature with that alignment is the following;,

Lawful Evil. (LE) creatures methodically take what they want, within the limits of a code of tradition, loyalty, or order. Devils and blue dragons are typically lawful evil.

But the most important thing to keep in mind is that alignment in 5E is a loose concept and you can vary from that typical behavior, which few are perfectly and consistently faithful to the precepts of their alignment. 

Alignment: Individuals might vary significantly from that typical behavior, and few people are perfectly and consistently faithful to the precepts of their alignment.

So players should respect each other's way of playing their characters and don't overthink or sweat it, it could be as little as your Paladin often becoming just a little more selfish or merciless regarding laws and codes, more pitiless to martyr and suffering or not even much  it's all up to you in the end and what you're ok to put up with.

Quote from Acromos >>

I'd say: Make it clear to the GM that you're not having any. Inform him or her that your character is - obviously - aware of this shift in perceptions, and dislikes the new person they've become. And that they're going into therapy (or cloistered meditation, or whatever) until they can reestablish their moral foundations, and then roll a new character. Make it a LG paladin of Ilmater for good measure. 

The GM does not get to change characters - other than by the reduction of hitpoints.

There are canon items that mess with your alignment, so the writers consider messing with alignment to be within the purview of the DM. 

That said, I'm a strong advocate for the concept that characters belong to the player; I'd hope that if one of my players felt a move like this was not conducive to their fun, they'd come speak to me about it and we'd work something out - even if it meant withdrawing the curse. Or better, that I'd obtain permission before doing it, either in a session 0 or by asking as I'm about to inform them of it (or both).

It appears that the DM isn't of that attitude though. If I decided I wanted to continue in a campaign that was insistent that I do something I really don't enjoy, I'd play into the implicit nature of evil in D&D - not moustache twirling jerk, but selfish and self-centred. I might labour to maintain the illusion that I care about suffering...but be willing to look the other way when it suits me and nobody will find our. Or I might employ unsavoury methods to obtain my goals. I'm no longer working for the Greater Good, but for the Good of [insert my character name]. Often the two may well coincide. Other times not.

In the context of D&D PCs, good and evil isn't about Tolkienesque Aragorn v Orcs, but the balance point between the "Greater Good of Society" versus the "Greater Good of Me". You don't have to be a jerk to play the latter - although it will naturally lead to less cooperation.

I've always considered Good and Evil on alignment to be based on how you treat or consider "Others". "Others" are, in this case, people you have no previous dealings or attachments towards.

Other party members are not Others, Loved NPCs are not Others. Random peasants in need of aid, or the noble you've never met who is hurting them, they are "Others".

If the welfare and wellbeing of "Others" factors highly in your decision making, you are good.

If the welfare of "Others" factors in your decision making, but less so than non-"Others", then you're neutral.

If the welfare of "Others" doesn't factor highly in your decision making, then you are Evil.

So you wouldn't become a jerk to your friends, nor would you even seem much changed. It would be when a peasant approaches the group for help saying their village was burnt to the ground, and your character says "And?" - that's when they should notice the difference.

Now if your character finds out that their beloved NPC goblin was in that village, then they may elect to help to avenge them, but not because an "Other" asked them to, or because it helps "Others".

Ilmater is the god of compassion and the enemy of suffering. 

So, I’d suggest following a rigid code, broadly compatible with Ilmater’s teachings:

- Be as party constructive as possible (lawful, aid your allies). Be the most generous of your group, but only within your group.

- Ensure the foes of your group suffer as little as possible, by killing them as efficiently as you can (evil)

- Donate your share of the proceeds of your party’s inevitable looting to the nearest temple of The Crying God, and pray for his mercy and forgiveness. Pray that he guide your hand in the battles to come. Pray that the suffering be brief. Pray for the strength to endure this burden.

Explain your creed to your allies. Be penitent. 

Evil characters can be the most helpful and honest characters in the party, especially lawful evil - unambiguous, straightforward, rock solid allies. No sneakiness, lies, underhanded deceptions needed;  say what you mean, help your allies to your last breath. You will still be racking up a colossal kill count, 100% evil, and with luck you might even have the lawful-good party members questioning their beliefs a little. 

Have fun!

Quote from Linklite >>

There are canon items that mess with your alignment, so the writers consider messing with alignment to be within the purview of the DM. 

 But I do not. 

If I were the GM I would have talked to the player beforehand to get them onboard if this were something important to the campaign. That way we could discuss how the PC would change.

I wouldn't throw something like this at the party willy nilly.

If you aren't interested in playing an evil character, that is a discussion to have with the DM;  maybe they can escalate the cure or let you retire the character and roll up a new one for the time being.

If you are at least game to play the character for the (hopefully) limited amount of time (and the DM should at least tell you how long this might last, even in vague terms, so you aren't stuck doing this for a years worth of sessions), then I would think about it the following ways:

1) An alignment shift is not necessarily a "Dudley Doright becomes Snidely Whiplash" overnight transformation, nor is it a personality overwrite, but it does imply some sort of shift in the PCs thinking.  Perhaps this manifests as a loss of empathy with others, or an amplification of the PC's faults (arrogance, vanity, wrath, etc).  If it is a loss of empathy, the character could become apathetic to the suffering of others, or begin demanding bribes or payment for assistance (possibly to an extreme).  An example of this might be beginning to require "protection" money similar to the mob, and withholding help from those who don't pay.

2) It might also manifest in a more extreme outlook on punishing those who cause suffering, choosing to kill rather than knock out or arrest, etc.  

3) either way, your PC hasn't likely broken their oath simply by having their alignment changed, but their actions might certainly do so in the future.  In one game i was a player in, we had a PC paladin who ignored their oath, and rather than becoming an oathbreaker, their class powers were diminished until they atoned.

I'm blanking on the name of the sects now, but I do recall there is one (or more) sects of Ilmater worshippers who take the god's goal of easing suffering in the direction of taking vengeance on those who cause suffering. In some sense rather than "healing the bullied" it becomes "bully the bully until they stop" sort of approach to Ilmater's ideals. Which isn't inherently evil, but is also only a few small steps away from "I like hurting bullies" and from what I recall, that sect is portrayed as sliding in that direction, yet still proport to be devout Ilmater worshippers and haven't directly been cut off by Ilmater yet.

And, to be fair, even Ilmater personally has done some pretty harsh actions to punish evil. I'm only familiar with this since our campaign has directly touched on it, but one of Ilmater's first major actions and his initial team-up with Tyr was the Procession of Justice. Basically, the human nation of Jhaamdath got pretty warmongering and started invading elven nation of Nikerymath. Elves doing their usual of never going by half measures, used high magic to create a tidal wave and wipe out nearly every person in the nation - soldier, leader, commoner, young, old - everyone. The few survivors who weren't drown by elven mages unsurprisingly fell into some anarchy in the immediate aftermath of a nation-wide natural disaster and massacre. Few years later, Tyr shows up and Ilmater teams up with him on the Procession of Justice, not to help the survivors of the massive disaster but instead to "pacify" the region with an army of archons.

So, as much as Ilmater is about easing the suffering of those in pain, and is generally a pretty kind FR deity, he is not above personally assisting a celestial army in attacking the survivors of a massive disaster because they were doing too much banditry. ;) So maybe a LE Paladin of Ilmater could lean into that side, and maybe think of "Batman when he goes way too far" sort of angle perhaps?