Destiny 2's Forsaken expansion begins with Uldren Sov escaping from the Prison of Elders, but I thought his whereabouts were unknown following the events of The Taken King. Is there writing somewhere that explains what he was doing between The Taken King and Forsaken?
edit: I think I was mistaken about Uldren Sov escaping from the Prison of Elders. He traveled there to break the Barons out of the prison, but I don't think he was imprisoned there himself.
Best Answer
Uldren Sov was indeed imprisoned there.
Following the events of The Taken King, everyone thought both Uldren and Mara Sov were dead. However, Uldren somehow survived, and ended up shipwrecked on Mars.
There are hints he might have an affliction of some kind, after he survived the blast at the Battle of Saturn.
Uldren spent some time with his allies from the House of Kings. At some point in time, he confronts Illyn, as described in the lore entry Free | Part I:
In the next entry, Free | Part II;
Petra Venj makes sure that only those three - Cayde-6, Petra, and Variks, know that Uldren Sov is in the Prison of Elders:
Variks, who is the warden of The Prison of Elders, does not know where his loyalty truly lies. After a while, he shows that his loyalty lies with Uldren, opens all cells in the prison, and escapes through the same secret passage that they used to smuggle Uldren through undetected while the prison is in chaos.
Uldren escapes, and continues his campaign to free his sister, which he believes is still alive.