Captain, your Blackthorn info is slightly erroneous...
That is one of the most complex lore issues in the game....kinda hard to explain, but basically, Blackthorn died in Ultima 9 before UO was created, but UO is a seperate world from the original Ultima games because Mondain's crystal ball broke into different shards of immortality which all became exact copies of the original world, but developed differently, hence why we have different shards in UO.
Ultima IX was released
after UO in September of '99.
So, the original UO Blackthorn lived in Felucca, because Trammel had not been invented yet. The Felucca Blackthorn is dead, you can actually go to the Felucca Blackthorn castle and visit his grave.
The lore written about Trammel, what it is, why it was created, and all that type of stuff is....well....it's crap lol, none of it makes any sense. So, in modern times, the developers and EM's decided that they would sort of "edit" the messed up lore about Trammel so Blackthorn would still be alive.
Now, they say that when Trammel was created, Blackthorn basically got cloned....or something.... so even though the original Felucca one is dead and buried, his Trammel clone has been around this whole time, and was just in hiding until recently when he saw the Kingdom needed him.
As for him being evil, he was actually a really good person originally and was a good guy, but the Guardian, who was an evil boss in the original Ultima games, corrupted him and turned him evil.
So, since the one that got corrupted and turned evil was the Felucca one who is dead, that means the Trammel one was never turned evil, therefore is still a really good person and fit to rule the kingdom.
Complicated enough? hehe
Er... It's actually way more convoluted than that
So, Lord British and Blackthorn were close frenemies, at least ideologically. Lord British had his Virtues, while Blackthorn preferred Chaos. Now, Chaos to Blackthorn is not the psychotic evil most think, but more a sense that each person should more or less govern themselves and not have a bunch of restrictions and morals forced on them by the state. (Ignore the Order vs Chaos guards, as that was just a lame way to try adding structure to PvP and had little fictional support)
Lord British also wanted to follow the Time Lord's warning and reunite the shards of the Gem of Immortality to prevent the Prime timeline from imploding. Blackthorn, however, though that idea was monstrous as it would
kill everyone on every shard except for the original. (Since the nature of the shards is dimensionally recursive, meaning each shard has
more shards inside of it, the death toll would be staggering)
(History without the retcon) So... Blackthorn was corrupted by the Shadowlords in the prime timeline (single player Ultima games), UO's Blackthorn was corrupted by Exodus and
assimilated augmented with Exodus' technology, wich is actually technomancy (magic and technology combined).
(an aside about Exodus: Exodus, according to the prime timeline, is the psyche/soul of a daemon magically housed in a machine (computer) body. Mondain and Minax used alien tech (Kilrathi) to create Exodus, who they saw as their "son.")
This upgraded Blackthorn allied with Kabur the Juka and resided in a keep in central Ilshenar and made trouble for Britannia.
(June 2003) His last attack on his former nation occurred in Yew, where a young warrior named Dawn managed to slay him. He was entombed in the courtyard of his keep in Felucca with several shards of the Gem of Immortality. (Note: Dawn had actually been created to ascend to the throne and reign as Britannia's Queen, but EA mismanagement sunk that plotline)
(2009) To fill the political-figure-corrupted-by-the-Shadowlords-a-la-Ultima-V role, Casca was created. He was also killed by Dawn, who subsequently ascended to the throne.
(2012) Britannia had been in a leadership vacuum since Queen Dawn's death at the hand of her ensorcelled husband. Enter the retcon!
As the plague in Ter Mur wraps up, we learn that the Blackthorn who perished all those years before in Yew was actually a replicant/clone/android that Exodus
pulled out of his... created. The
real Blackthorn had actually been held in stasis somewhere and only managed to escape when the new technorganic Exodus was sent back to cybernetic Hell. He came up with the cure for the mysterious plague, fixed the problem with the moongates, and somehow
conned impressed whoever was currently in political power into making him King. (If you want to get really
, you might wonder
where the gargoyle's plague originated and
how Blackthorn just happened to have devised a cure so soon after being defrosted.)
So now, as King of Britannia, he sits on a gigantic, S&M-y phallus throne in a massive, ostentatiously decorated castle looming over Britain.