Black Manta is kind of a wild character because we have to pretend that Aquaman is a major DC character and BM is kind of his main adversary, apart from Ocean Master and lame jokes about his Superfriends version. But despite debuting in 1967, he wasn't given an origin until 1993.
In the first one, Manta was a kid from Boston who was kidnapped by abusive pirates. He saw Aquaman and his dolphins and tried to signal to him, but his calls went unanswered, so he swore vengeance on the superhero and the entire ocean.
The autism and Aquaman as his hyperfixation origin came in 2003 (see below).
And, of course, this was after quietly dropping his earlier motive; in 1977, he took off his mask and revealed that he was African-American and the Black Manta name was a racial thing, because that's how they named Black superpeople in the 70s. His suit also developed electrical powers around this time, because he was a Black guy in 70s superhero comics. He wanted to conquer Atlantis and make it, and possibly the entire ocean, a home for Black people. He stopped bringing it up because it was either considered cringe and politically tone deaf (Doyalist) or he talked to literally any other Black person (Watsonian).
In 2011, he was a treasure hunter with a wife, and they were captured in the Bermuda Triangle by the extradimensional people of Xebel, the underwater alien culture that Aquaman's wife Mera is from. His wife was carrying their child and it developed water powers or some shit, so Mera kidnapped the child, and took it to earth, Black Manta's wife died, and he returned to earth. Very convoluted shit, and it really makes Mera and her people look like monsters. But this was also the first time he was even given a real name, which his Wikipedia page oddly bolds as David. I like the idea that his name has to be bold. Imagine a supervillain whose name is just John.
Eventually, in the New 52, he was made a descendent of some Atlantean exiles, and a pirate whose father was a pirate killed by Aquaman. In one of his most infamous moments, he, in turn, kill Aquaman's kid. And he also just showed up to murder Atleaneans and other supporting characters at a remarkably high frequency, because Aquaman writers are obsessed with making Aquaman fucking hardcore. HE ISN'T SILLY SHUT UP.
And then in 2016's DC Rebirth, they brought back a lot of the pre-New 52 continuity. And every time Black Manta shows up, the writers seem to roll on a d100 chart to decide what version of him is in the current story.
Except for the weird underwater black nationalist thing. That's buried under the rug.
