> The Battle of Aeonia / Radahn and Malenia locked in stalemate / Then, the scarlet rot blooms.

I've been thinking about the theories suggesting that Radahn's battle with Malenia is primarily a result of his great rune corruption, or that the whole thing was planned in advance as a part of the vow with Miquella.

However, even if it's given that all of these are true:

- During his youth, Radahn agreed to become Miquella's consort

- The vow involved a duel as a test of strength with Malenia

- Radahn's great rune, which increased his size and amplified his power, also affected his reasoning 

Then it still makes sense that the Starscourge would back out from the promise to Miquella. And it would be for a simple reason:

> **Radahn alone holds Sellia secure**.

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During the context of the Shattering, the 'greatest of all wars', Caelid faces threats in basically every direction:

- Morgott wants to re-assert authority over the province

- Rykard would love to gorge himself on Redmane warriors

- Godrick's army snatches up anyone it can for grafting

- Cuckoo knights raid and steal everything that isn't bolted down, and Sellia is filled with magical artifacts

- The Lord of Blood is operating directly under Caelid

Radahn simply can't afford to abandon his post and go mess around in the Shadow Realm, even for a little while. He would refuse to leave Caelid, and certainly not for a duel that could leave him incapacitated. So long as the Shattering was going on, it follows that Radahn would make no accomodations for a promise from his youth, because his adult responsibilities are more important. He must defend Caelid.

Of course, **Miquella & Malenia face the same pressures**: They can't afford to wait around another another demigod grabbing the lordship or ascending to godhood, especially as the rot continues to advance. They need to go to Radahn, and to do that they have to cross several battlefields with an army in tow. 

But the Redmanes can't be seen to allow an outside army to walk in unopposed - it would signal weakness, or otherwise indicate an alliance that the other demigods must unite to oppose. And so Malenia's crossing into Caelid is an act of war, and the duel that was promised becomes an all-out apocalyptic battle.

**TLDR**: All of Caelid was at risk in that battle, even if Malenia didn’t use the scarlet rot. Radahn and the Redmanes absolutely needed to throw everything they had at the Cleanrots.

Radahn was right to defend Caelid