Look at the double standards...
"Shattered across space and time" (by hearsay): LITERAL OMNIPRESENCE, LEGIT
"I'm holding a piece of him right now" (we literally see it: NOOO, METAPHOR, CRYPTIC, NOT LITERALLY!
Do you mean that I've been applying double standards in that regard?
If so, I do apologize if I've bothered with you with that, but I didn't mean to; I have had no intention of applying double standards, whether I've been (unwittingly) doing so or not.
That said, to "play Devil's Advocate" as they say:
If to treat those two differently in regards to figurative vs literal qualification is a double standard, then I'd like to ensure I better know what the... erm... "standard standard" for the two is in this case. So....
Why would him being shattered across space & time be metaphorical?
Gaster was an incredible scientist, his work being, IIRC, unfathomable & revered by everyone, especially Alphys, the 2nd best scientist of the Kingdom, & whom took over in his absence.
Yet his works are considered beyond her scope, skills & understanding.
At that level, something that could shatter a being across time & space isn't unheard of. & thanks to Chara & Determination, talk of timelines & time & space all that isn't unprecedented within Undertale. That it was his own creation which did this, when Gaster fell into it, rather than some other machine of some other origin, I think reaffirms this.
- Alphys might work faster. But the old Royal Scientist, Doctor W.D. Gaster?
- One day, he vanished without a trace.
- They say he shattered across time and space.
- Ha ha... How can I say so without fear?
- I'm holding a piece of him right here.
This guy is speaking in rhyme, the thing he's holding doesn't look like the "Mystery Man" we associate with Gaster, it moves -Odd if it'd be a piece that's shattered- & looks like a head.
This clam-headed monster talks about how he came to Hotland from Waterfall specifically to get a drink. He comments if the protagonist carries a glass of water[1] and if they dump a few glasses of, or all of the water on the ground.[2][3] If the protagonist poured all of the water out of the...
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Plus, his own dialogue asserts Gaster "vanished without a trace", so what's he doing having a trace, a piece, of Gaster? It seems like a self-contradiction to me.
& that assumes it's even possible to hold a piece of Gaster who was shattered in such a manner.
It may be of note that they disappear after their dialogue.
So this guy is talking in rhyme, his assertion of holding a piece of Gaster seems self-contradictory, the thing he's holding doesn't match the primary suspect for Gaster's appearance (Which doesn't move, unlike what he's holding.), & is a head, which would ostensibly be too important a piece to say you're holding a "piece".
Gaster was the royal scientist, & other dialogue claims he's listening; If you had his HEAD, still moving, of all pieces, you'd probably say you're holding his head, rather than "a piece".
& if it's not that head thing, then what? An invisible piece?
Being shattered across time & space feels like a more sci-fi statement that's meant to be genuine exposition & aligns with stuff featured in Undertale.
But holding a piece of him feels contradictory to a lot, & like it's meant to be a dramatic twist for surprise creepy in the dialogue.
Not to mention the possibility of a reverent follower of someone being likely they have a "piece" of the target of their idolization, when they in fact, do not have a literal piece of that being, because they feel a strong connection, especially an emotional one.
When these guys are, IIRC, canonically called Gaster Followers, like "followers" of a cult, & practically are, behaving in strange, creepy ways, spreading word of this dude -& then creepily disappearing, too.- who supposedly got "shattered across time and space" after falling into his own creation, I can believe that less science-y parts, especially creepy twists at the end of their dialogue might be a little bit less literal.
Also, forgive me if I did or gave the impression that I did, but I don't fully believe Gaster is omnipresent. At least, given what little info we have.
It's possible he is, but I don't think we have enough to support such a conclusion, currently.
We don't know how many pieces, what trajectory, what speed, when.... The scenario where he's asserting to be listening is just one, & from a follower I'd call reverent, given their dialogue:
- I understand why ASGORE waited so long to hire a new Royal Scientist.
- The previous one... Dr. Gaster.
- His brilliance was irreplaceable.
- However, his life... Was cut short.
- One day, his experiments went wrong, and...
- [Talk again]
- Well, I needn't gossip.
- After all, it's rude to talk about someone who's listening.
I do apologize for any bother caused by the stance(s) I currently have.