That would be interesting.
I think one of the Famitsu scans had Ven walking with Terra in the forest full of thorns, so I we will probably see a somewhat moving Ven in 0.2. I am now looking even closer to the scene where Aqua meets them at the hill, and it seems that VenÂ´s eyes are closed. So in a way he really is "sleep walking" or what ever he is doing.
I am pretty sure it`s Guardian who grabs Ventus. Darksides have sharp and pointy claws, and that thing that grabs Ventus seems to have normal fingers like the Guardian.
Yeah, it`s possible that Xehanort learns about him there. Hirokey had an interesting idea that Xehanort could also learn about the chamber where Ven sleeps in that scene too, by Aqua explaining to Terra where Ventus is. I can imagine it now: Terra and Aqua being worried about Ven`s odd state, Aqua tells about Ven`s location Terra to calm him and shit goes down.
I am also wondering since that might be Terra`s heart and Terra`s heart had darkness in it, maybe the Terranort/Guardian that appears there is the manifestation of Terra`s own darkness?
It would certainly give an interesting spin on showing "updates" on Ven's status somewhat without going too much into meta-heartstuff.
Considering the wound his heart suffered from destroying the X-blade prototype was worse
than the one inflicted by Vanitas' creation I can easily see why Ventus would be in such a situation and largely unable to speak or act even as a projection.
When he first came to Land of Departure he also was still in a pitiful state despite Sora helping to stabilize his heart and actually collapsed due to Terra just asking some questions (granted, Terra was a little pushy there, but still), which Nomura described in the BBS Ultimania as "Ven's heart having not yet fully formed again" which may be a synonym for "not fully healed".
In the four years between Ven's arrival and the begin of BBS proper Ventus does develop in a good pace due to Terra, Aqua and Eraqus caring for him and Terra actually mentions to Xehanort that "Ven got much better since then (then speaking about when he first came to LoD)".
Ventus being so broken and frail at the beginning might also have contributed to the somewhat overprotective stance both Aqua and Terra take on him during BBS itself.
Now I imagine Aqua seeing Ventus in that state again and how painful it will be for her knowing he's so broken and suffering yet again, not to mention that if Terra is really consciously there how much of a gut punch it will be for him, especially when Xehanort's taunts of "how powerless he is to save his friends" may still echo in his ears.
Sounds reasonable about it being the Guardian then, I haven't the anatomy of Darksides fully in my mind so I'll just trust your word on this.
Hirokey's idea sounds actually pretty solid since several things would fit together that way, not to mention the bitter irony that Aqua and/or Terra might have given away Ventus' status and the location of his body and soul inadvertently
to Xehanort, their worst enemy who's responsible for all their suffering.
The idea of all this being a manifestation of Terra's own darkness could also give a totally different spin to the scene with the Guardian.
Looking at the screenshot I don't see Terra there at all, only Aqua, Ven and the Guardian.
If that "Guardian" is a manifestation of Terra's Darkness instead of a controlled minion of Xehanort, maybe the Guardian "grabbing" Ven is actually a misaimed protective gesture made by Terra in his despair whicn only drives him deeper in, eventually losing control fully and then
Xehanort himself makes his appearance, laughing at how Terra still can't control even his own darkness and possibly sarcastically thanking Aqua for all the information she has given him.