Someone shared this very interesting thought about Sephiroth on Reddit, and it would be an understatement to say that it excites me. Quoting my own thoughts about Sephiroth over the years here (and not anything in this reddit post):
"Sephiroth would have made a better anti-hero than a villain as a character because his struggle with the truth while wishing to remain good would have been an AWESOME conflict with Hojo as the villain and Jenova as his burden... Insanity was the easy way out."
"Sephiroth's insanity makes no sense because his values and personality both do SUCH a 180. He's such a different person. Why have a 'good' Sephiroth in the first place? It's a tragedy for tragedy's sake. It doesn't feel personal or real..."
In a nutshell, the user in this post is using the scene at the end of Ever Crisis ch. 8 as evidence that suggests Edge of Creation Sephiroth, a.k.a "Ore" Sephiroth by some commentors, is in fact a different Sephiroth from all the others seen throughout the game antagonizing Cloud (Please read the post for your own interpretation). The user suggests that this Sephiroth was legitamitely reaching out to Cloud as a person (and not a puppet) for help. And, honestly, I have to admit that through my initial playthrough of Remake, Sephiroth genuinely asking for help was my interpretation of that scene.
Why? Because villain Sephiroth would NEVER ask Cloud for help as a manipulation tactic. Because asking for help in any capacity is an antithesis to his "being above everybody/being beyond human/A God I Am" existence. He would COMMAND Cloud to work for him (as he does throughout the game) or just take control of him, not ask him to help him. Why ask for help? And why ask Cloud? It was, in short, out of character for villain Seph who can't see Cloud as his equal...or himself needing help for that matter. That's precisely why he is the (sad) villain/antagonist in the first place.
Naturally, my thoughts on the believability of Sephiroth's fall to insanity have changed drastically with Rebirth's version of the Nibelheim scene. Drawing on everything we can know about Sephiroth at the point when Rebirth came out, his fall to insanity (discounting sleep deprivation, possible dehydration, possible food deprivation, and just...not dying/being debilitated by any of this maybe due to his Jenova cells...like his actual mom not dying...) is presented less as a sudden change and as more of a bitter realization, an overwhelming sadness, and a refusal to let that break "him"--he who was "chosen and blessed" by the planet (cannot convince me that child Sephiroth wasn't a bit of a planetologist and that he did not believe that he was special because the planet chose him to be strong). In short, it thematically makes more sense when you know Sephiroth traumas and tragedies...as well as who's responsible for them (Hojo. It's always Hojo). I stopped saying "If only he learned of Lucrecia in that basement..." and started realizing "Oh. He knew... He just grew bitter about her, Professor Gast, Hojo, Shinra, and every goddamn tragedy that happened in his life because of his 'conception/creation' (he conflates these words in the cutscene for a very good reason). Damn."
Evenso, I could not change my other opinion which can be summed up as "Good Sephiroth is, thematically, a good character for the FFVII story in the sense that he could have been the anti-Jenova and Shinra's (and Hojo's) greatest enemy as an anti-hero." It would have been a good "this is what you get for trying to play god and disrespect the planet" story, and good Seph would not have felt so wasted.
I, presently, feel like Sephiroth's good traits would not have just disappeared so to speak.
Despite accepting his insanity, I still feel like his new self is such a contrast to his old that they can't be the same person.
They aren't the same person.
And while I can better suspend my disbelief and just chalk it up to "he experienced psychosis, had a moral event horizon, and now embraces himself as a monster destined to become a god to fulfill that role," I just cannot shake that "Ore" Sephiroth is more that an attempt at manipulation if I do so. Thus, I can't help but agree (and, really, hope because I am very much snuffing hopium on this) that this user has the right of it and that "Ore" Sephiroth is a different Seph.
One commentor added to this belief by pointing out the canon truth--that villain Seph has cast off everything to the lifestream (by AC) except his hatred of Cloud and desire for godhood. This commentor went on to suggest something along the lines of these discarded memories and emotions--the "humanity of Sephiroth"--becoming his own individual who is actively fighting against this evil version of himself a la the way Villain Seph and Aerith are, and I kind of like that because it could add another layer to Sephiroth's breakdown as a person--
What if Sephiroth's personality did not flip (like a switch) as many of us have always thought?
What if Sephiroth's personality split within the same person?
Sephiroth's good-self and desire to be a good person and hero vs. Sephiroth's bitter-self who casts off humanity and chooses to stand above them (in the most unforgiving and violent way possible)?
I COULD very well believe in Sephiroth splitting personalities (in a fictional sense as we have seen it done before) and becoming so different precisely because he is different right down to his core, a darker Seph overwritting his kinder self and then, ultimately, casting him aside in the lifestream.
Talk about something that fits the current Remake/Rebirth's themes on how reality/memories work in the lifestream. And you would continue the trend of "sticking to the OG story, albeit with changes" by having a good Seph, a villain Seph, and him staying dead at the end of the game (and maybe being with his friends and loved ones in the LS) as a result of him resolving his emotional conflict.
Of course, all of this is speculation breeding speculation. We will know for better or for worse come part III, but I would LOVE for Square to go all in on this and truly explore Sephiroth's story in a new way (just as we are with Cloud, Aerith, Zack, and maybe Tifa). Villain Seph would not see "Hoisted by His Own Petard" (i.e. casting aside his "useless" self) coming back to bite him in the ass...and it would be so fun to see that absolutely destroy his shit-eating grin once and for all.