now that i'm about halfway through dirge of cerberus, i went back and replayed remake intergrade, chapter 2...
the thing that stuck out to me the MOST is that the deepground lackeys or whatever the hell you wanna call them are totally outfitted for long range combat when they fight yuffie and sonon. i also remembered WAY more members actually being there- but in all actuality you probably only see 20 or so members, including the ones nero murders (out of boredom or for power? another day.)
but they're all equipped with their stupid like, range enhancing helmets that would fucking impossible to see out of at short range (hello security officer helmet, but at least that thing doesn't cover their whole head.) and they're all wearing pants, which begs the question. was it just a small sample size (~20 members) or did they change the deepground uniforms in the three years inbetween remake intergrade and dirge of cerberus? 'cause they're totally wearing different outfits depending on their gender in dirge of cerberus- their thighs are OUT if they're women. but all pants in intergrade. did we only fight men, or was there an outfit change...?
also nero has split pupils (cat pupils? idk the right word) like sephiroth... is that just a jenova thing? if so, why don't more SOLDIERs have eyes like that??
Yuffie’s mission in Midgar ended unsuccessfully. Shinra destroyed the base of her allies in Sector 7, she couldn’t get hold of the Ultimate Materia and, most importantly, Sonon died in order to save her.
His death gives a sense of closure to this newly introduced character. Although being quite short, the DLC is full of clever parallels between Yuffie and Melphie, Sonon's younger sister who got killed in front of his eyes during the Wutai war. He failed to save Melphie back then, but he can save Yuffie now.
But the big question is: is Sonon really dead?
The OST playing during the death scene is Seeing Melphie again. After getting stabbed, he has a vision of his little sister (a very touching moment tied to FFVII theme of reunion in the afterlife) accompanied by a bitterweet piano melody, that gets always softer until his last breath. But just when Nero seems to finish Sonon off, instead of mercilessly swallowing him into the darkness, he gently picks him up while the music digresses in an ominious and mysterious tone, hinting that his role may be not over yet.
I think the answer may be deduced diggin a bit into Dirge of Cerberus lore.
There's a not very well known entry related to the main DoC game (especially by the western audience since it had been released only in Japan and for a very short period of time): Dirge of Cerberus Multiplayer on-line. While some of the missions were later included in the international release of DoC, the plot of this game got lost despite its importance for the full understanding of the Deepground dynamics.
Here is a link for an excellent article from thelifestream.net that tries to keep a record of this expired entry, and here's a playlist of cutscenes from the game with English subtitles that helps understanding the main plot (btw, a great YT channel where you can also find localized playthroughs of rarities like DoC Lost Episode and Before Crisis).
Deepground is a top secret facility created by President Shinra and located beneath the slums (remember that underground lab where Cloud, Barret and Tifa went to save Wedge? That's Deepground) where troopers and SOLDIERs - but also unaware civilians - endure severe experimentations that push their bodies and minds to the limit, aiming to create ruthless SOLDIERs with no moral boundaries. The elite DG SOLDIERs are known as Tsviets, like Weiss, Nero, Argento, Shelke, Rosso and Azul. To avoid any rebellion each candidate and Tsviet has a restriction chip implanted in their brain controlled by four Restrictors loyal to President Shinra. This mechanism is particoularly useful to control those Tsviets who don't make a distinction between allies and enemies.
Because of this the Tsviets started to secretly plot against Shinra until they finally understood how to cheat the system. Shelke and Argento found a way to implant a non-working chip in a candidate, so that they could kill the Restrictors. The protagonist of DoC Multiplayer is indeed this candidate (gender and name chosen by the player). Thanks to her special abilities Shelke tricked the candidate into seeing a supporting partner, Usher, who helped them into ranking as a Tsviet, and most importantly she instilled the hatred towards the Restrictors giving to the candidate false memories of a little sister brutally killed by one of them. In the end the candidate managed to kill one of the Restrictors but got stabbed as well. This is the final dialogue of the game:
Weiss: Can this one still be of any use?
Shelke: Negative. The prolonged SND [Synaptic Net Dive] has rendered most of the brain inaccessible. It's only a matter of time before it breaks down completely.
Rosso: Really? After all that hard work. What a shame.
Weiss: Then hurry up and find a suitable replacement. After all no one knows what the Restrictors really look like.
Azul: So we have to find another one? This is becoming frustrating.
Weiss: It can't be helped. Only one out of hundreds can make it this far.
Rosso: Ordinary humans simply aren't as strong as we are.
Weiss: Precisely.
Shelke: Well, it's actually quite simple. With the help of the HJ Virus I am able to hack into Patricia [computer system] and bypass security. Then all that's needed is to pick a suitable subject before it's implanted with the chip.
Weiss: Shelke, find a new one quickly.
The devs had never provided any time reference for the Multiplayer story but now, with Intergrade, we know for sure that the Tsviets are still under Shinra's control when Yuffie and Sonon met Nero on December 12, and, while the President will be killed the next night, it seems clear that Scarlet is the one who will take full control of Deepground until her defeat the next month.
My theory is that Sonon could be the perfect person to replace the Tsviet-candidate and the dead Restrictor, so that Weiss and the gang can pursure their plan of rebellion gainst Shinra:
Unlike many soldiers Sonon has proved to be an extremely strong and capable fighter standing up to Nero.
He has the right motivation as he seeks revenge against Shinra - especially Scarlet - for the death of his younger sister, which Shelke could further manipulate.
Unlike any other Deepground candidate, he has no working restriction chip implanted.
Sure, one could argue that Nero severely wounded him, but the game clearly reminded us before the battle that Nero can easily disintegrate the bodies of his victims, while he reserves a different treatment to this particoular character. And, by the way, this wouldn't even be the first time a Tsviet pretends to kill someone as Shelke did the same with the Tsviet-candidate. As far as I know the main DoC game never explained how the Tsviets overpowered the remaining Restrictors, who replaced the Tsviet-candidate or what happened to Argento - who isn't part of the DoC cast. Sonon might be the missing piece of this sub-plot that may lead to new secondary arcs that could tie a bit more Deepground to the main FFVII story.