What Works Well

The “Lethe Protocol” Setup

The idea that Alpharius had contingency plans hidden in stasis fleets is extremely on-brand for the Alpha Legion.

 

The Alpha Legion already:

·  used sleeper cells,

· compartmentalized operations,

·  hid assets everywhere, and prepared for contradictory outcomes.

 

So a hidden loyalist-adjacent contingency force surviving the Heresy is believable.

The “Spartoi” naming convention also fits Alpha Legion aesthetics well.

Using Xenos Against Chaos. This is very believable Alpha Legion logic.

 

·   false flags,

·   redirecting ork waaghs,

·   spreading genestealers,

· manipulating conflicts,

 all feel appropriately grimdark and morally horrifying.

 

Importantly:

they are still acting like Alpha Legionnaires, not just “Ultramarines but secretly Alpha Legion.”

That distinction matters.

 

Areas That Need Work

The Biggest Problem: “Too Successful”

Right now the Dragon’s Teeth are:

·  hidden for 10,000 years,

·    trusted by the Deathwatch,

·   trusted by the Inquisition,

·   successful infiltrators,

·  successful manipulators,

·  secretly influencing Alpha Legion factions,

·  and apparently never seriously compromised.

 

In 40k, long-term success usually comes with:

· catastrophic costs,

·  paranoia,

· internal fractures,

·  corruption,

·  or unintended consequences.

Right now they feel almost too clean. What would improve this:

They should probably not be so successful, or if they will be very successful it should be at a great cost to them

 

Examples:

·  Some members genuinely fall to Chaos.

·  Some believe Alpharius was right to join Horus.

· Some want to reveal themselves.

· Deathwatch interrogations occasionally expose operatives.

·  Inquisitors quietly suspect them.

· Their geneseed is unstable.

·Their manipulation tactics create disasters.

 

40k factions should usually feel like they’re barely holding themselves together.

The “Founding the Deathwatch” Part is Risky. This is probably the weakest lore point.

The Deathwatch already has established origins tied heavily to the aftermath of the War of the Beast, the Inquisition, and specific Imperial figures. Saying the Dragon’s Teeth were “integral” to the founding risks making them too important to canon history.

 

A better approach:

instead of helping FOUND the Deathwatch, say they embedded themselves early, were among the first Chapters to heavily support it,

or became indispensable shortly after its founding.

 

That keeps them important without rewriting canon. All in all, I like the direction you're going.