...how to make a generic character feel as important and meaningful as any of the Origins.
I just don't think it's possible. I think it's a great goal, and it's an understandable want... but I can't imagine how a custom character could compete in a story that could otherwise be dedicated to a known entity.
There are things to do to make the custom character feel a little more invested, sure. NWN2 starts the main character in West Harbor, by the Mere of Dead Men. And this gets referenced throughout the game, giving the main character a sense of home, of history, and of beginning.
IMO, the key to making the "generic" character just as important to any of the Origins is to focus on
forward looking content, instead of trying to cobble together a compelling but also generic backstory.
The specific appeal of the custom character is that it's not tied to the hyper specific origin stories (which many characters do not identify with), so trying to force fit something into there will just defeat the purpose of the custom character.
In well designed story, the background is just a minor point of detail. True character is decided through actions and decision during the actual course of the story. For example - the Bhaalspawn wasn't truly defined by what happened in Candlekeep for the first 18 years of their life. It's what they chose to do after the call of adventure that truly formed the character. Similarly, while the Nameless One may have gone through multiple incarnations that setup the course of his current story. The true
character of the Nameless one, the one you care about, is ultimately decided by the choices and decision you make during your story.
What does this mean for the BG3 Custom protagonist? It means adding in content/questlines ONLY for the custom character that will really give you an opportunity to define who you are. There's multiple ways Larian can do that. For example:
1) Upon enter Baldur's Gate, you go back to your neighbor and find the people that raised you are missing, and are forced to unravel what has happened...
2) Your "dream person" tells you they're in danger and needs your help, and draws you into a dream adventure
Regardless of how it starts, the goal of these quests isn't to go a X and kill Y, etc. It's to challenge the player philosophically and force them to make decisions. Push comes to shove, who are you really? What are you willing to give up for the people you love? What do you truly believe in, and how much are you willing to give up to fight for it. I'm thinking some Witcher-esque tough decisions that aren't entirely comfortable. Remember, all the origin characters - their goals, motivation, and characteristics are ultimately pre-defined. Whereas the custom character doesn't come with that. What this custom content should do is to allow you to stew in these kind of thoughts and decisions, and really work out who your main character is.
And I don't mean to imply that the main game/plot won't have important choices. However, ultimately the urgency of the main plot really doesn't offer you that same chance - since regardless of who you are (evil, sociopathic, altruistic, empathetic), you are heavily driven into self preservation and thus your choices really are limited to doing anything that will get you closer to the cure. Everything revolves it. The custom character's well defined past helps fill in tons of character gaps. So it'll be great if the custom character's special content precisely addresses that gap, I think that would be a great way to make the custom character feel special and truly your own.
