Aside from what Andrew Hussie wrote, and what I wrote on my LordOfClasspect blog about lightbound. There is something I wanted to go further into detail about that is pretty evidently clear in all examples of Lightbound that I think is pretty interesting.
So basically, aside from knowledge Lightbound are marked by an extreme challenge with Morality. Hussie describes that lightbound tend to find loopholes around the rules. This generally works out for them but it becomes a problem in that they often times end up with a distorted or grey perspective of morality, which leads into a tendency that when they do Wrong, they are explicitly Evil and marked by a curse.
Rose Lalonde tried to loophole the game Sburb, and in the process directly destroyed the game's architecture and doomed the entire session even for her friends. Nearly casting them all out into the Void to be eaten by the horrorterrors. Whether explicit or implicit she became the villain defacto. Even her alcoholism in general signifies that she doesn't care enough to recognize that even her seemingly lowly necessary Seer title was absolutely critical and responsible for the success and wellbeing of not just herself but her friends as well. Similar to Dirk's darkest bout of negligence towards his friends but more direct, straightforward and exact.
Vriska snapped the spine of an innocent and continues on destiny's path as if she will face no consequences. Constantly hijacks the plot and spotlight regardless of whether this is actually optimal or not. Her best character development came when she was humble and beating herself up as an inverted expression of her role. Then she could face up to her direct fault and flaws.
Aranae becomes so selfish she will literally doom another version of herself to do it, trying to make herself Alpha by force. In the process she disrupts both Jake and Dirk, Jake in a fundamental way and makes it clear she has no qualms with hurting Dirk to get what she wants. She goes from an extremely patient and kind being to one of impatience and grey morality.
Outside of Homestuck Canon, you have Rick Sanchez, who is an apt example to bring wider representation. As Rick Sanchez is a Lord of Light. Recently it was revealed in a canonical short written by Justin Roiland that Rick is in fact Morty. Rick hands Morty a potion saying that it's from excretions from the memory parasite in season 2, and that it will turn Morty into Rip Van Winkle. He also overlaps his reflection with Morty's face, and points saying "Rick Sanchez". Thus it's officially confirmed Morty is Rick, and the implications and realizations for what this means are endless.
For one, it puts things in perspective. Throughout the entire show Rick and Morty's stories run right alongside each other. And it clearly paints a contrast and shows the way the world works for Morty compared to how it works for Rick. There's also countless references and scenes that completely change context if you realize they are actually synchronized time events synchronizing Rick and Morty in a way that makes it plainly clear that due to Time Shenanigans, everything Morty does and goes through influences and changes Rick's character, memory, etc. So much so to the point that it's obvious everything Morty does IS Rick's actual back story, and Rick "already did it" before, as it's defined when Morty does it for the first time.
The realization is clear. Morty is bullied, is dumber than others around him, and struggles hard to keep up with others. Somewhere along the line, originally, Morty just shifted into prop comedy and entertainment like his father Jerry, before eventually getting into Science and realizing that the mathematical, concrete, and absolute nature of Science played really well with his Asperger Syndrome. He then at some point invents a portal gun, and explores the universe. At some point he flies under the alias Rick Sanchez, which in the real world is a notorious alias for people needing a fake identity especially people who have done so many crimes they can never get clean.
Rick and Morty are so opposite it's not even funny. Yet that's what makes this so obvious. Somewhere along the way Morty has an Ego Death because of how the universe treats him, and he evolves into everything he wasn't. This is why Rick suffers and explains his absolutely nihilistic and cynical view of the world. Because as Morty he learned the hard way that the universe does not care about you, does not play fair, and will just keep pushing and pushing with no limit. Eventually he just snapped and flipped it around so at least he always wins.
Now the relevance here is astounding. As Morty he was a Muse of Void. Inspiring the Void but in a Blackwing way. Morty seems innocent and harmless and like the Hero, but his actions always invariably lead to suffering, death, and evil. Evil Morty is predominated Morty and makes it clear that Morty is just in all ways inherently Evil and Destructive, but in a Passive way. Rick in contrast may contradictingly claim he doesn't care, thinks morality is bullshit, and does things which are morally fucked up. But inversely when challenged by the Devil, has a special passion for wiping him in the dust. Meanwhile even his worst acts which seem on the surface to be so reprehensible that they are unforgivable, what we are shown are things which with a good enough reason to balance it out, actually makes him a Savior.
It's actually Morty who is contradictory. Void is ambivalent and while Voidbound have half Light in them, Morty is the one who is ambivalent when it really matters and doesn't actually care when he absolutely should. Only to challenge Rick's authority and to rebel does Morty act like he's the good guy that really cares. Needless to say if we read the entire story a different way, Rick was inverted originally. As a single entity he became Light more and more over time, but it was a long process of trial and error. In the process to becoming the All Powerful Rick, Morty carries a lot of Moral Baggage. Every Rick has done something virtually ubforgiveable but continues moving through the universe running on as much borrowed time as he can get. Not really deserving everything he has and is but continues on anyways. Changing the Rick and Morty story in a very keen way if you view it as 1 continuous character both ways. Making Rick appear more like Vriska.
Basically if we view it as 1 singular and linear storyline. Then Rick is trying to run along after doing whatever evil and trying to escape the very consequences he created in the process. Nevermind that Morty gaining so much knowledge and changing personality so radically has warped his perception of everything so radically. That he can hardly tell right from wrong, and has no sense of what he is or isn't allowed to do. And technically he has the power to back it up. So much so it's hinted throughout the show of how Morty would have abused his science to do things for his own personal gain. Fridge Horror stuff.
The point is this is a perfect example of what I mean about Lightbound. Even Thor from Marvel Avengers has the fact that his family has a history of Genocide, and it's in his own veins as much as it was in his father's.
Lightbound embody the aspect of Perfection and Holiness. But as it has become obvious this has to be a story of a flawed mortal BECOMING the epitome of this... And God/The Universe is so forgiving and encompassing that nobody said you couldn't break a few eggs to make an omelet. What matters is where you end up/the destination/your intended goal.
Lightbound may mess up more than others, and in vastly worse ways than other Bound. But they succeed more than others do, and go farther.