*Gives Jarrod a telepathic high-five*
Morrison tied into Claremont's original story...Phoenix is not an entity. Jean as Phoenix was Jean at her evolved state(prematurely). It's her mutuation(and obviously, Rachel's as well). The retcon screwed this all up, made it into a force, and worst yet, a sentient force...however even within the silly retcon, EVERYTHING, its form, it's ability to communication, etc, derived from Jean...while dying on the shuttle, she jokes "oh great, so you're a figment of my imagination"...which if you think about it, for a telepath, is not so far from the truth. At any rate, there's a part from X-Men: The Hidden Years #9 that sums it up perfectly IMO.
In X-Men:The Hidden Years issue 9, there's a "dream
sequence"(moreso like a vision), and Phoenix(inhabiting Jean's body) says "Incredible! The untapped power in this body is almost limitless!", and soon after Cyclops says in thought "It's as if all of her natural inhibitions have been stripped away!".
Now the Phoenix Corps thing isn't "elegant", in fact by itself i hate the idea, but given the fact that everything is hamstrung by "shitty continuity", it was necessary to allow for other instances of "Phoenixi"...still though, Jean is the Queen Bitch of the all(White Phoenix of the Crown...a nod to when Jean was in white Phoenix form while visiting Death after her death on the Moon in Claremont's backup story in Classic X-Men 43). As for the "Black bubbles"...there are two things going on here. One is the power, which is based on mutation. The other is the Consciousness...that is still really murky, but at least decentralizes things and doesn't make "Phoenix" to be some retarded cosmic crow with a necrophiliac "dead red head" fixation. But like i said, from what i've seen of Phoenix Endsong, it seems to be doing the cosmic crow thing. This is what I hate about minis....they get some hotshot writer...he does some spotty cliff's notes "research" on a character, picks and choses what to use, puts it in a blender, adds a cup of rat piss, puree, and slap it on paper. Sorry, but when your favorite character is Jean Grey, you have to be a cynic.
And back to Rachel...like i said, i have no problem with her(and i'm quite learned with regards to her character, and i do have the entire Excalibur run in digital form)...I have a problem with how she is used, and in a lot of ways it's as a replacement(hell, first it was just to keep the copyrights to the Phoenix name). The minute Rachel shows up, Jean becomes either the crazy bitch, the dead bitch, or the crazy dead bitch. And yes i know about the holempathic "heart to heart" between Jean and Rachel...still though, that's just a convenient but thinly veiled attempt to cover up the fact that once again, she's there to pretty much sub for Mama.
I'm sure Storm fans would love for her to be "cloned/possesed" by some "Jet Stream Force", almost destroy the planet, die....and have some dimension displaced daughter called pop up, claim the name of Storm, have the exact same powers but free of the stigma of her Mother.