I am quite into the story of the Awoken race and what was happening to our favourite Awoken characters during both Destiny games and one thing that bothers me is how close were both Cayde-6 and Uldren to Petra from what we can gather.
Petra and Cayde felt almost like a fireteam, working together in a pair anywhere they could on the Reef, even communicating secretly between Reef and Tower when they could and Cayde expresses feeligs of strong friendship he had with her in one of his Ace of Spades mission chests. His death was something that made her not question killing Uldren in revenge, even tho Uldren was her close friend as well.
But is it possible that she was prepared to kill Uldren not only for revenge, but out of sorrow of turning him against her? There are clues leading to Uldren and Petra being closer than one could see, even tho there is not much of them. But in one of Lore entries we could learn about how painful it was for Uldren to give up on Petra during his secret plan with Scorn, while Petra is described as being joyful and then depressed after the return of Uldren and revelation of him going crazy, talking about Mara being alive.
Important nod to all of this is in Black Talon's tab, describing Petra as a broken person, that wants to believe that both Mara and Uldren are alive, so much that she is unable to join *Uldren's* memorial. Another thing is her own quote: "Even if I can't excuse his crimes... I sometimes miss him. I can't help it." He was close to her. Definetly. She always felt proud to be under command of Mara and Uldren, both talking casually together about things and news when these two could, she sometimes quoted his feelings about Guardians back in D1 and seemed really into what he says.
So my conclusion is that when she decided to kill Uldren, it wasn't just because he killed Cayde, she mentioned that the Ghost, who knew what Uldren did to Cayde, didn't know what he did in reality. What I think what he did in reality was breaking her completely, most importantly her affection and trust in him which actually hurted her more than Cayde.. then of course there is this thing with annihilation of The Awoken which Uldren also did, which could set her off, but.. if it was about that, I think she would definetly antagonize him more like Adolf Hit--r and spit on his grave whenever she could.
But since she felt strong connection to him, I think that she actually wanted badly to excuse his crimes and have reasons not to kill him, but it was like breaking the closest and only friendship two people could have, maybe even a romance, but definetly only on Petra's part. Uldren probably was closer with his friend with which he entered Black Garden than with Petra, tho I don't believe those two were romanticaly involved like some people point out.
Lore masters, I call upon you to help me out with this soap-opera thing that I am probably digging too much into, and help to resolve if it was Cayde who was closer to her, or Uldren. :D
Also, do you think that it will move in some way with Petra when she finds out..
WEEELL - SPOILERS - SPOILERS - SPOILERS
..that Uldren is alive as a Guardian, so a good guy again, but without any memory of her and of Mara? [/spoiler]
Uldren wasn’t revived. That was a scrapped cutscene made to come out at the end of Forsaken but they realized how stupid reviving him would be so they scrapped it. Petra cried for Cayde when he died, Petra put a bullet in Uldren. Kinda shows who she was closer to.
The Reef had poor views on both mechanical beings as well as the Guardian, so unfortunately, Petra likely only saw Cayde as a tool to help her get control of the Reef in their more chaotic times. She could've made an actual friendship with him, but it seems unlikely given the stigma she was brought up on. Also, Petra's anger with Uldren was sourced in the fact that he helped the House of Kings pillage the Reef, not that he killed Cayde.
The reason she felt more anger towards Uldren than we thought she would is because Uldren was already turned to the darkness. Uldren already betrayed his people before Forsaken. Petra also had a good relationship with Cayde before his death. Think of it like this, one of your worst enemies who you used to love, turned against you and killed one of your best friends. That’s probably how Petra felt, but I do think before Uldren betrayed the Awoken, she would’ve had better feelings.
Uldren and Petra were also close. Both had an unwavering devotion to Mara Sov, and actually worked closely together.
In fact, the event that got Petra demoted in the first place was a bombing she ordered on a large group of Fallen with guardians in the proximity. Three fireteams were killed in the process, leading to her demotion.
Prince Uldren was the one who carried out the bombing run.
The reason why she fell head first into her anger was because she felt personally betrayed by Uldren. He had, after all, slaughtered his own people.