Do the Primals Know Each Other?

[Allyrion]

But I remember Minfilia actually mentioning how crazy it was that not only did Iceheart take the form of a Primal, but that she retained control of the form.
I'd have to re-check my cinematics to find it, but it was one of the things I couldn't help take note of. I remember even re-reading the sentence to be sure.

I'm assuming my character got the impression Iceheart was in control, and said it in silent dialogue since it was never explicitly stated during the quest or in the battle.

[Veritas-Ancora]

I still want to know how Iceheart is still alive. Gurl, when you go primal you never go back.

[Anonymoose]

I still want to know how Iceheart is still alive.

Based on the word choices of Minfilia, Nabriales, and Lahabrea, my assumption is that she used the Echo to make the walls of her soul permeable (the Echo seems to make your soul more sensitive and less rigid), thus allowing the, for lack of a better term, Essence of Frost to inhabit her by way of aether and prayer. She seems to have been able to prevent her spiritual form from being altered inn any way while still allowing herself to become a physical vessel, and then we beat that aether-enhanced vessel up until the essence withdrew, either due to expending the aether used to summon it, or by weakening Ysayle too much to be a suitable host.

Alternate Fringe Theory:
If Ysayle is fit to host Shiva, and Shiva was robust enough to lay with dragons...

[Allyrion]

Okay, so for the source that she retained her will, it was actually Thancred who said it.
It was still matter-of-factly said though, and doesn't seem to be something we should doubt.

It's the first cutscene from the quest, Eyes Unclouded (Princess Mononoke reference? I think so!)
I'll transcribe it -

PC explains events.
Minfilia: Iceheart used her own body as a vessel for a primal's soul?

Y'shtola: Master Louisouix's writings make no mention of such a possibility. Can we be certain this entity was a primal?

Papalymo: As certain as we can be that Good King Moogle Mog XII was a primal, I should think. Both were ostensibly summoned.

Thancred: Let's not quibble over definitions. Of more concern is the implication that Iceheart retained her will even after she was possessed. We are talking about a mortal wielding the power of a primal!

Yda: It can't possible be that easy, can it? There must be some sort of sacrifice required. Or maybe she's just special?

Urianger: What qualities this woman possesseth, I know not, but full sure am I that she was groomed for this role.

Then Urianger basically says it's probably the Ascians, since they're the ones with something to gain from summoning and dissemination of a Primal.
Moenbryda, then, says that Shiva was certainly a Primal or something very similar to what we've been fighting, due to the readings.
Y'shtola surmises we need to relook at our past encounters.

Actually quite interesting to look at them talk about Louisouix and this process without knowing that he did something similar himself.
I have little doubt, from how that dialogue goes, that Iceheart had control over Shiva.
It sounds more like a transformation (Super Saiyan-esque) than anything else.

[LineageRazor]

All I really mean is, "Let's take Enkidu with a grain of salt and for now not use it as a metric by which other primals can be measured." In a quest line that has intelligent, dapper zombies - being cured of zombie-ism in a way even the NPCs find incredulous - and multiple instances of surviving explosives to the face and falling hundreds of feet without a scratch, I prefer to err on the side of caution. I don't mean to say, "Enkidu is in no way representative of the primal phenomenon." The instant I get that confident is usually right before the instant where I end up eating my hat on a technicality.

Let's not forget, as well, that the individual summoning Enkidu was a very unique and special individual. Just because Greg could do it doesn't mean that we need to be concerned about any Tom, Dick, or Harry summoning a pocket-primal willy-nilly. It may not be fair to dismiss Enkidu as a legitimate primal out of hand.

[Nestama]

I'm inclined to believe that Enkidu isn't a summon at all and has been Eorzea all this time (well, about as long as Gilgamesh has been). A 'giant bird-like creature' or something of that nature had been mentioned once or twice in 2.2 (and possibly later, but I can't recall). Also, weren't the elemental crystals supposedly used in Enkidu's summoning fire (I don't remember)? If so, then... doesn't that kinda throw the entire "can only be summoned by the crystal representing their element" thing out of the window? Enkidu is quite clearly of the wind element.

[Anonymoose]

<...> Enkidu <...>

They were, indeed, fire ... but they vanished just as he was (for want of a better word) praying.

O, Enkidu, wherever you may wander! Hear my words, and return here to my side! Enkidu, do you hear me!? ENKIIIDUUUUUUUUUUUU!
Ye gads! What was that flash from the heavens? It nearly blinded me! And...what!? The crystals! Where have they gone!?

This led Hildibrand to conclude that Enkidu was a primal, but even other NPCs thought it was dumb.

By the gods, it makes perfect sense! Doubtless the crystals heard Greg's heartfelt plea, summoning forth his friend─nay, no mere friend, but rather the primal Enkidu!

...And the world has now completely and utterly ceased to be bound by the laws of logic.

This is the source of my hesitation to conclude without a healthy dose of skepticism that they're not just exaggerating lore for laughs.

[Risvertasashi]

After the initial scene when our characters wake up from our 5 year stasis that Louisoix put us in, it's more just dialog changes rather then full scenes being changed. One I can recall is when you meet Minfillia again she comments about not forgetting who you are and how you have echo... but then proceeds to explain what Echo is like we were an ARR player

Are there any other scenes or is it just this? I haven't touched my legacy character since the relaunch, but there's a number of dialogue changes that might just tempt me...

[Rocl]

Are there any other scenes or is it just this? I haven't touched my legacy character since the relaunch, but there's a number of dialogue changes that might just tempt me...

There are a few, depending on your progress in 1.0's 7UE scenario. References to you slaying Nael van Darnus in Second Coil, Cid saying something "oh didn't I tell you? this is the second time <player name> has saved Eorzea!" after Praetorium, etc

[Atlaworks]

I'm pretty sure all the primals went to high school together. Extrapolate your high school castes at your leisure.