That is the one million dollar question.
Though I specially like the phrasing: "Guided by the calls of the Planet". Seems Gaia still has it's sense of importance in all of this.
Yes! Gaia indeed is still reaching out.
One of the more confusing aspects of Remake is, what is the relationship between Aerith, Gaia, and Sephiroth? If Avalanche was fighting against destiny, doesn't that kinda mean we're fighting against the planet? Or at least, disagreeing with it? If Sephiroth is an enemy, then the Planet becomes a type of nemesis or another character we are in tension with.
My headcanon explanation is as follows:
1) the Planet is still a relatively good character, albiet it, something divine and beyond the conventions of good and evil. Meaning, it does what it has to to preserve itself and life, even at the expense of some of its inhabitants (think WEAPONs, Holy, etc which sometimes go to war with humanity).
2) JenovaRoth has infected the Lifestream and the Planet in its travels through the Lifestream. This has resulted in some spirit energy, souls, and memories become corrupted and under the influence of JenovaRoth. This is why some Whispers are Dark and "normal" while others are Purple. Purple clearly indicates a type of Jenova infection. This could explain why the Whispers were generally trying to influence Sephiroth away from changing the fate it destined for itself, but also why some Whispers appear to go against it (see chapter 4 end, where one Whisper in the voice of Sephiroth almost whispers lullabies to Cloud, keeping him sleeping).
3) I think the fact that the Whispers look scary is a sign that the planet is unwell, and is, dying. Aerith says, after the Whispers scream aloud in chapter 18:
What you heard just now were the voices of the planet. Those born into this world, who lived and who died. Who returned. They're howling in pain.
Cloud says explicitly in response: "Because of him? Sephiroth?" Aerith nods in agreement, and explains why Sephiroth is unaffected by their influence, unlike how they can influence others.
They... their words... they don't reach him. All these moments and memories, precious and fleeting... they're like rain rolling off his back. And when they're gone, he won't cry... or shout... or anything. He'd tell you that he only cares about the planet. That he'd do everything in his power to protect and preserve it. But this isn't the way it's supposed to be. There's no greater threat to the planet than him.
The last line seems clear that Sephiroth is not trying to destroy the planet, but preserve it in the way he think best. This will naturally result in the destruction or the corruption of Life, including the Whispers and the Lifestream.
Note: This is why I do not believe Sephiroth is after the black materia. He does not want to destroy the planet anylonger, but has something else in mind. The reason why he scares the party with images of Meteor is precisely to get them to chase him. He needs something else from them.... I'm more confident in this because, why would the devs spoil the ending of Remake already?
4. This is the part that is very confusing. Finally, to stop Sephiroth/Jenova and their corrupting influence, Aerith realizes that they have to destroy the Whispers. But does this mean Aerith is against the Planet, since the Whispers are just remnants of the Lifestream that carry out the planet's will? We need clarification on what these Whispers truly are. My gut tells me, they are simply WEAPONs of the planet, and not the planet's will itself. Just like the party destroyed Ultima WEAPON and Diamond WEAPON in OG, this does not mean you are fighting the planet itself, but rather it's misguided efforts to preserve itself at all costs. Meaning, if the Whispers are destroyed, the planet's will is intact and can be convinced to see a better path.
