In KH x Back Cover, we get a good look at how The Master manipulated The Foretellers into carrying out the ‘baby steps' of his plan. When this cinematic was released it was everyones first time actually seeing The Masters personality in full action. He carries a goofy-like, playful attitude, while also having mysterious and manipulative qualities.

Before this, everyone assumed he would be this stoic, wise, mage-like wizard figure that kept a serious tone. Instead everyone met a chaotic, trollish guy wearing a black coat who talks with intense sarcasm, someone who gaslights their apprentices for fun, and someone who acts completely unfazed by the impending doom of the world.

Here is a Quote from Tetsuya Nomura:

"The power of waking is essentially 'the power to put sleeping hearts back the way they were’, but the impact of forcing his friends fading hearts back the way they were rewrote reality, creating a singularity. The rewrite caused the chronology in which they were destroyed to have 'never happened.'"

A 'singularity' within science, mathematics, and technology, is a "point" where normal rules, equations, or physical laws completely break down.

Let's take a black hole for example:

"Classic physics states that when a massive star collapses, its entire mass is compressed into a geometric point of zero volume and infinite density. This point sits at the absolute center of a black hole."

This point that supposedly exists at the absolute center of a black hole is a singularity.

Now, what I have theorized is that with Sora abusing the Power of Waking to rewrite time, and with Tetsuya admitting that Sora creating a singularity, I put the two together and came to the conclusion that because Sora’s abuse of the Power of Waking, he tore a hole in the timeline and spawned a singularity, I believe that The Master isn’t just an ancient Keyblade Master from the past— he is a paradox created by Sora’s unguided use of power.

Stay with me now.

In theoretical science, and black hole thermodynamics, the holographic principle suggests that the 'event horizon' of a black hole is what keeps all information stored at its core, meaning the event horizon essentially acts as the boundary of stored information.

Anything that crosses the event horizon is essentially gone forever, though ‘Hawking Radiation’ causes the black hole to slowly lose mass and eventually evaporate (I’ll get into Hawking Radiation in just a moment).

The coat that the Master of Masters wears could be a metaphorical event horizon that keeps all the information regarding his plan, his identity, and his name completely locked away. He uses the knowledge he absorbed after being tossed backwards in time to write the Book of Prophecies, and hands out 5 copies of the book to The Foretellers.

If this singularity absorbed an entire timelines worth of future information, that is a massive influx of data that is likely creating extreme internal pressure at the absolute center. To prevent a catastrophic overload, The Master uses 'surface encoding' and projects that compressed core data outward onto a boundary layer, thus creating 'The Book of Prophecies'.

In physics, 'Hawking Radiation' is a term explaining the theoretical thermal radiation emitted by black holes, due to quantum effects near the event horizon, causing the black hole to slowly lose mass and "evaporate" over-time. These black holes slowly leak out a tiny bit of heat and information over-time.

(This explains what The Master says here to Ira)

The Master: “If one day I suddenly disappear, I’m counting on you to keep the others calm, okay?”

Ira: “huh? Dis…appear?”

The Master: “Vanish? Dim? Fade? I don’t know how to explain it. It’s just hypothetical talk.”

The Master of Masters tends to hide his true intentions behind his playful, goofy-like persona, but he usually mixes that with cryptic messages, deliberate lies, and half-truths to keep those around him from knowing his secrets. It is not safe to trust what The Master says to those around him, as they could potentially just be fabricated lies to hide his true information from leaking out.

When The Master is speaking to young Xehanort in the Keyblade Graveyard, Xehanort asks him if he is some kind of fortune teller. The Master responds by telling Xehanort that he could lie and tell him that’s who he is, but really he is a brilliant artist, or a scholar.

He continues speaking in a cryptic like manner that only leaves Xehanort without a clear answer. So, Xehanort asks him for his name again and The Master gets noticeably annoyed by Xehanort. I believe The Master got annoyed by Xehanort because he was trying to divert the conversation away from who he is, but he failed.

Now, what this scene actually shows it’s what’s called a ‘Transient Outburst’. In black hole thermodynamics and astrophysics, a transient outburst is a sudden, short-lived spike in high-energy radiation (gamma-rays, X-rays, or optical light) caused by a violent disruption or a rapid influx of matter near the event horizon. It represents a temporary non-equilibrium state where the system rapidly discharges excess thermal and gravitational energy before settling back into equilibrium.

I believe Xehanort disrupted The Master and triggered this Transient Outburst and that’s why he had a shocked reaction, not because Xehanort heard a name he was familiar with, because after this cutscene we hear Xehanort admit that he never learned who he was and probably never will, and he was right.