So there’s something that’s been bothering me about Epyon

[Dark Duel]

Some time ago I started rewatching Wing, an episode or two at a time when I could.
And there’s something that bothers me about the development of Epyon: the fact that it’s equipped with a ZERO System.

To the best of my recollection, the five engineers collaborated, along with Howard, on the development of the Tallgeese, then subsequently left OZ/The Alliance, and secretly collaborated in designing Wing Zero - and presumably the ZERO System around the same time. Zero itself was never built, and the five went their separate ways with each creating his own Gundam.

So how did Treize get his hands on it? Has there been any kind of explanation for that?

[ShadowCell]

OZ also had the five Gundam scientists captive before the Epyon's reveal, and also captured the Wing Zero itself after Quatre's rampage, so unless i'm misremembering the chronology of events, they could've just gotten it that way.

[Seto Kaiba]

So how did Treize get his hands on it? Has there been any kind of explanation for that?

The Wing Gundam Zero was captured by Heero and Trowa on OZ's behalf in the same episode (No.25) where Treize gets forced out of his position in the Romefeller Foundation over his opposition to the Foundation's plan to replace Mobile Suits with Mobile Dolls.

OZ had plenty of time to study the ZERO system prior to the Epyon's rollout almost ten episodes later, and there were likely no shortage of Treize Faction OZ soldiers willing to leak the data to him.

(Of course, OZ's security was so lax they either missed or didn't care that Treize was building a Gundam in his summer house's garage like a f*cking hobby car... so for all we know they let him take the Wing Gundam Zero home on the weekends or something.)

[Dark Duel]

OZ had plenty of time to study the ZERO system prior to the Epyon's rollout almost ten episodes later, and there were likely no shortage of Treize Faction OZ soldiers willing to leak the data to him.

Guess that makes sense. Leaked from someone at the lunar base with access to Wing Zero and the data gathered from it. Perhaps a modification made while the machine itself was already under construction.

[Wingnut]

According to GoL, Treize had been building Epyon for some time, and IIRC, the manga has that one shipment of Gundanium alloy that Heero shoots down after he canabalizes Deathscythe for parts was intended to help build Epyon. The inclusion of the Zero System seems like a late addition to the design after Q started blasting stuff away in space with it.
Though I have to agree that someone(s) managed to get all the findings to Treize after the initial studies of Wing Zero and what it can do (and more importantly HOW it can do them).

[MythSearcher]

Come to think of it, if one can trace all of the purchase of Quatre when he built WZ in his own backyard, which isn't too far fetched when you are controlling the world and already knew where the Gundam pilots came from, Zero system is likely just a software hacking process (or maybe even easier, a copying process, if it was not even protected)

[Arsarcana]

The latter seems likely, given the evidence in the series. Not only did Quatre manage to reproduce the system from the original plans on his own but Heero and Zechs were both able to create modified versions of the system (the ones that Quatre and Dorothy use for tactical coordination late in the series) with no apparent difficulty. The scientists who designed the system never expected it to be used and the Gundams were expected to self-destruct to prevent capture so they might not have bothered with much in the way of software protection.

[MythSearcher]

The Zero system is too much of a failure as a military installment anyway. Most of the soldiers will pretty much go insane or just die when using it. So they may not see any reason in protecting a project they decided to scrap.

Unlike the Tallgeese, which you can simply put a software or even a hardware limiter on the propulsion and anyone can just drive it out for a ride with not danger whatsoever(given s/he at least know how to control it), the WZ's Zero system can't be simply modified to a usable state.

[HalfDemonInuyasha]

The Zero system is too much of a failure as a military installment anyway. Most of the soldiers will pretty much go insane or just die when using it. So they may not see any reason in protecting a project they decided to scrap.

Unlike the Tallgeese, which you can simply put a software or even a hardware limiter on the propulsion and anyone can just drive it out for a ride with not danger whatsoever(given s/he at least know how to control it), the WZ's Zero system can't be simply modified to a usable state.

Just look at the 1.5 and 2.0 versions on the Wing Gundam Lucifer and Seraphim; one only enhances the detrimental effects while the other essentially makes the choices for you via taking control of the mobile suit.

Even with the modified version Heero made for Quatre, Quatre still struggled to keep it from controlling him and promptly removed it after the only battle it was used in. Dorothy never uses it again either, and even Zechs only uses it once in terms of controlling other mobile dolls as escorts.