"Darkstar" is introduced in Heroes & Villains as the supervillain name of the once-superhero Starburst.
Vereint Georges has always dreamed of being a superhero like his wall poster crush Blue Ice. So when he gains superpowers (strength, flight, invulnerability, speed–the basic package) he sets out to be what he thinks a superhero should be.
From the haircut, to the "I’m a superhero" voice, to the almighty poses, he uses them all.
And as a result, his superhero persona Starburst is universally mocked by reporters and superheroes alike. Including Blue Ice.
In a confrontation with Blue Ice, Starburst discovers some kind of new ability where violet light auras out of his body and melts everything it touches. He barely manages to stop it after it melts a section of street and sidewalk (and possibly a fire hydrant? I have to go back and reread that scene).
For a second, he’s proud of himself that he managed to get control. He looks up and catches Blue Ice’s–his hero’s!–eyes, and expects some kind of praise or something. Instead he gets derision and a general sense of "Get your shit together."
Vereint continues on as a superhero for awhile, but eventually snaps and decides that if he can’t be a hero, he’s going to be a villain and do whatever he wants. So during the annual Good Day Parade, he robs a jewelry store.
And that’s the start of his criminal career.
Stealing things. Displaying his powers to crowds as they hand off their wealth and goods. Trying out different outfits and looks to the enjoyment of the masses. And obliterating anyone that dares to confront him.
Every time Vereint "powers up," his metabilities grow.
In the Heroes & Villains universe, he falls in love with Warrick and retires from the super-life. There are occasions where he’s forced to power up (and violently kills a bunch of people, sorry to the squeamish) which grows his metabilities. But for the most part, his metabilities are just simmering under the surface, growing, but slowly. It’s more of a natural progression than Kanon-Darkstar’s power growth.
Because Kanon-Darkstar constantly uses his metabilities, his Charm is off the charts. It’s to the point where it’s more than just a registered weapon–his section of Megacity is under permanent quarantine.
Because while Kanon Darkstar can and does leave his Megacity to visit other places, he lives there and sleeps there most nights.
HV-Vereint can "power down," basically damp himself down so much that he’s practically a normal human. More durable, stronger, but at his depowered base he could still push a car or jump onto a second floor roof. It’s when he wants to move heavier things or do more metahuman stuff that he has to tap into his "inner power." But as long as he’s powered down, his Charm isn’t effecting the people around him. There’s not tendrils of influence going out, scrambling peoples’ brains.
Kanon Darkstar has kept himself powered up for so long and for so hard that even in his most depowered state, he can’t help exuding Charm around him.
And, as is revealed in–I think Allies & Enemies or Tuesday Night–one of the stories, a metahuman being around a stronger metahuman can make them stronger. (It’s all about the manna and the nectar zions and all that stuff from Timeline. It doesn’t matter for exposition purposes.)
Kanon-Darkstar is a powermaker.
Him just living in an area, exuding his presence all over, results in stronger metabilities in those that would have Manifested without him, and in metabilities developing in those that would have had a dormant Nor-gene.
In Allies & Enemies there’s statistics mentioned in the news about something like 80% of the population possessing the Nor gene, with most Manifesting minor abilities. Stuff like being able to grow their fingernails or heal their own skin. Minor stuff.
In the Kanon-verse, there are a lot more powerful metahumans because Darkstar is polluting the air around him with his very presence. And the more powerful metahumans there are, the more metahumans they effect and help create.
Kanon Sunfire is stronger than HV-Sunfire, and has displayed a much stronger–and deadlier–photokinetic ability as well as a devastating level of Charm-ability. Meanwhile, Kanon Melissa Kim becomes a superhero, but her powerset is a bit different from Blue Devil’s and she can’t fly.
no Vereint x Warrick = no adopted Melissa Kim = no Blue Devil
HV-Darkstar developed the gaussian blur he’s known for over time. There are clear photographs of the superhero Starburst, though everyone notes they look like different people. They could be brothers, but no one would think Starburst was Darkstar.
This is because while the gaussian blur is Darkstar’s metabilities visibly affecting mechanical equipment, it’s also a proof that his Charm is reaching out from his body. It shows up stronger closer around his head and face, but there’s no doubt that an invisible something is reaching out.
Because everyone that comes into contact with him is effected.
It is because of Darkstar that Charm is classified as one of the most powerful metabilities in the Kanon universe. So while the Heroes & Villains universe chugs along in ignorance, the Kanonverse understands that Charm is a horrifying and inexorable metability.
After a time, the League of Superheroes and other groups develop the use of "Charm proof" helmets for when they have to come into contact with Darkstar. But it’s well understood that the helmets will do nothing against long term contact or if the complete attention of Darkstar rests on someone. It’s better to not have him power up around people.
Thus the quarantining of Megacity.
He is treated as a god. Given everything and anything that he wants and whatever people think he might desire.
Some want his attentions upon them, feeling the burning glory of his presence against their skin and every bit of being.
Most people dread his attentions, glad to keep him appeased and within the confines of the Quarantine Zone.
"Darkstar is like a bear. A fucking dancing bear. He doesn’t know how to fight. He’s flailing around, punching and kicking and ‘oh look, I did a flip’ when it’s his ability to fly. But if you let that bear get its paws on you… it will fuck you up." — possibly from an LoS meeting where they watch video of Darkstar "fighting" a large group of people.
Vereint in Heroes & Villains has no real fight training. He never bothered to learn more than the basics he’s managed to pick up.
Kanon-Darkstar has more fight ability, but he’s still not "skilled" at it. Mostly because anything he hits with intent is obliterated.
It’s very hard to practice martial arts when you’re so strong that the world around you might as well be made of soda-lime glass.