So the Dream City gets overrun while Moyra Salve is away helping the guardians. Then, Utrim, who is the only other heir to the throne gets killed. Now, Moyra is "missing" leaving Preta as basically Queen without the title. Sorry, but this all seems a little to convenient. I think that Preta knew she would be in trouble for letting the Dream City get overrun, so she hatched a plan to seize power. First she had Utrim Salve killed and then she kidnapped Moyra. Preta knew she had nothing to lose bc Moyra would have never let her remain as he'd of guard considering her abject failure by letting the city get overrun. Talk about failing up.
Oryx ransacked the Dreaming City in the background of the events of the Taken King. Riven allowed herself to be Taken by Oryx during that time.
Then, later, Savathun took up control of Riven's strings for her own schemes. At some point, Uldren wished for Fikrul to be saved, and Riven took advantage of that to turn Fikrul into the first Scorn, and amplified the Darkness corruption the Black Garden infected him with to influence his decisions.
Then the events of Forsaken happened. Riven used Uldren in an attempt to free herself, and the Guardian and Petra executed him. We were sent in to kill Riven and cleanse her heart, and tripped the wire for the Dreaming City curse to take effect.
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Everything you've said is nothing but conspiracy and nonsense, completely detached from the story of the game.