Right of the bat, Bungie revealed that Destiny 2: Forsaken’s campaign beings with Uldren Sov, the Awoken Prince, kills Cayde-6 (Nathan Fillion). The rest of the DLC's campaign is centered on players hunting down Uldren and his associates in an epic revenge story. Though Destiny 2: Forsaken was initially billed as containing a new enemy race, it has since been confirmed that the former Prison of Elders inmates are actually twisted Fallen.
The Barons themselves, were once lowly Dregs, the lowest Fallen members possible. They were cast out from the House of Exiles but rather than whither and vanish, the 8 banded together and thrived.
After the Red War with the Cabal, Cayde-6, a team of elite Hunters and Awoken Regent-Commander Petra Venji hunted down the Scorn Barons and locked up in the Prison of Elders.
Uldren eventually breaks them out and they assist him in the dastardly deed. The 8 Scorn/Fallen Barons who serve as boss encounters at various stages in the DLC. Game Informer has released new details on each boss and we've got a recap that summarizes the key points.
Fikrul aka The Fanatic
The Fanatic is described as a Priest and is the lone Scorn Baron who escapes initial capture by Cayde-6 and Petra. He's the leader of the Skorn and views them as the Evolution of what the Fallen were always meant to become before they were abandoned by The Traveler.
He is second only to Uldren. It's also disclosed that he is a member of a long-lost, unnamed Fallen House who was banished for preaching that they should abandon their worship of machines. It's strongly hinted that when cut-off from ether, he found a shard of the Traveler to sustain him.
Elykris the The Machinist aka Elykris the Bandit
She is the Fanatic's second-in-command and described as an insatiable thief with an impressive arsenal of weapons. She's apparently something of a pirate, raiding ships and outposts and vanishing before the Vanguard or Awoken can mount a response.
Hiraks the Mindbender aka Hiraks Ascendent
Somewhat of a mad scientist, Hiraks focused his research on the Hive and modified himself to the point to where he can control Hive minds.
He apparently started out as a lowly Dreg and somehow fell into the Hive's Hellmouth on the moon. When he emerged, he never spoke another word. He's also somehow managed to carve out his own throne room in the Ascendant Realm.
Specifically, his base of operations is Asteroid 128 Nemesis, a former Reef outpost that now shifts between our reality and the Ascendant Realm.
Araskes the Trickster aka Araskes the Wit; Butcher of Bamberga and Terminus of the Gray Legion
She's a con artist and manipulator who works behind the scenes, crafting plans to get others to do her dirty work.
The only time the Trickster is sent to the forefront is when the Scorn must negotiate- she's their ambassador/envoy. Secretly, she has very little combat skills
It seems she uses a cloaking device, reminiscent of Nightstalker Hunters, that renders her invisible. Though she has several impressive titles, it's well known that she's actually made all of them up.
Reksis Vahn the Hangman aka The Godslayer
Rekkis was a Fallen member who was abandoned at birth. He has an especially devote hatred of Servitors for some reason. The Scorn's executioner, it's said that he led the assault that led to the extinction of the House of Wolves.
Kaniks the Mad Bomber aka Kaniks Two-Fingers
A teleporting Scorn Baro who loves to throw bombs and thinks very little of his own safety and self-preservation.
Cayde-6 puts it best, "Look, we all like blowing stuff up, but there’s a line. A line this guy crossed a long time ago."
Pirrha the Rifleman aka Pirrha the Phantom and Pirrha the Blind
A brilliant sniper with a penchant for taking out Guardian Ghosts, Pirrha's other-worldly aim is aided by a cybernetic eye and extensive surveillance network. He also works as an assassin-for-hire and has enough wealth to tempt even the most cautious of thieves.
Cayde-6's notes warn, "Trust me, kids: Keep your eyes open, head down… and your Ghost close."
Yaviks the Rider aka Yaviks the Untamed
Yaviks has upgraded her Pike and equipped it with a flamethrower to boot. She leads a ruthless band of riders that would all die at her command.
Her gang's appearance signals the start of Scorn activity and her crew also serves as a clean-up strikeforce, putting down and would-be survivors.