This post is missing a lot of context, which I should probably link to later. But here are some ideas @lunathrix had. (Part of the context is that at some point I decided all of the characters are gay furries now, and Luke in particular is a dogboy.)

Main idea: Luke was fully aware the Orb was made of chocolate and wanted to eat it from the start

As the middle way between dogs and humans, dog people are very intolerant to chocolate, but don’t die from it (unless they eat a ton maybe). 

Because of this, some more reckless dog people (deople?) want to eat chocolate even more as it is the forbidden snack

This is a commonly known fact, and as such other species will usually do their best to prevent deople from getting access to any chocolate

You know how you can broadly divide dog races into the group that got bred to do a few simple tasks (e.g. retrieving game for a hunter) who are great at listening to orders but have a dvd logo bouncing around in their heads at all times vs the ones that got bred to Handle Things on their own (e.g. herding sheep) and are the smart bois? Luke is a race of the former group and as a pureblood idiot wants nothing more than to consume the chocc

On his quest to acquire chocolate, he learned to disguise the fact that he’s a derson (dog person) by hiding his ears and tail like this (hey look it’s the idea that led to this whole google doc!):

This is nothing new for deople to do, Luke is just better at it than most because his parents helped him

It may seem counterintuitive that his parents are helping him eat the semi-poisonous food. It turns out they do love him but they are simply also idiots and also went on the same quest when they were young. So now they want to help him too!

For some reason he gets asked to help on the quest to recover the cursed orb. Somehow he also knows that it’s made of chocolate (there’s also some really good lore reason for the orb to be made of chocolate)

Maybe on his quest to acquire chocolate he’s helping everyone he encounters who needs it (because next to an idiot he’s also a very good boy) and his skill in combat is noticed?

 He accepts the quest seemingly because he just wants to help get rid of the cursed object. While this is partially true, he really just wants to eat it.

The fact that he wants to eat it is unknown to both the player, who only gets to see Luke’s dialogue and not his thoughts, and his party members, who are all various flavors of idiot and don’t see through Luke’s poorly disguised intentions.

The first person to notice his true intentions is the other person trying to acquire the orb in Rhapsody city

Despite being one of the first people in the story with more than two brain cells functioning at any given time, Luke ends up saving him in Rhapsody city from something really spooky or whatever. And then he bails with the orb (but feels bad about not giving it to the other guy).

Regrettably for him, he gets feelings for Luke after being saved by him, therefore becoming the (main?) love interest (enemies to lovers anyone?)

The Call to Adventure

Our hero, Luke Campbell, finds out he is THE CHOSEN ONE, the only one who can defeat Cursed Al. How does he find out? What is Al’s goal, and why must he be stopped? Why is Luke suited to the task?

Al promises eternal life, but it's really eternal damnation. He will steal your soul and force you to do his bidding. He intends to enslave the whole world. Luke is the only one whose soul is strong enough to not only resist Al’s influence, but free everyone else. He must hurry, however. If Al captures enough souls, even Luke will not be able to stop him.

How does Luke learn he is THE CHOSEN ONE? People have been going missing. Someone close to Luke disappears. Luke searches for them and learns of Cursed Al.

Refusal of the Call

Luke doesn't want to be THE CHOSEN ONE. Why?

Luke's just an ordinary guy. As much as he wants to find Sam, he doesn't know if he has what it takes to face Cursed Al. Of course, he eventually decides he has to try anyway because he loves Sam.

Supernatural Aid

Luke has no choice but to be THE CHOSEN ONE. James will be his mentor. Does James mentor him because he wants to or because he must? Have they met previously?

The Crossing of the First Threshold

Luke sets out on his journey to fulfill his quest as THE CHOSEN ONE. What causes him to change his mind? James's faith in Luke gives him the determination to continue. Of course, knowing that the fate of the world is at stake helps, but Luke's primary motivation is rescuing Sam.

Maybe the lost souls are forgotten. As Sam’s soul is drawn further into Al’s control, Luke struggles to remember them. Perhaps it will be a recurring theme that Luke will find something that reminds him of Sam. As he draws closer to his final battle, he'll remember some detail about them.

Belly of the Whale

Luke’s commitment to his quest is challenged. On second thought, maybe this wasn't such a good idea. He emerges victorious from his first major battle, and his resolve is stronger than ever. Within the game, this will later be recontextualized as not that big of a challenge.

Love interest for Luke.

His bond with Sam is so strong that it allows him to track their soul to Cursed Al. Luke's soul is also quite powerful itself, allowing him to use magic, but it's his bond with Sam that truly gives him strength.

With enough souls, he will become godlike. His essence is eternal, but there has always been someone to banish him. Souls taken by Al are gradually forgotten until they all but disappear from existence.