Daybit

Saber x Shirou was soulful and good written, because they were basically the same type of character. Both were broken human beings, who sacrificed themselves for others. Artoria decided to become a King even at human life's cost (like Merlin said), and her wish to Holy Grail was to save Britain. Shirou was Seigi no Mikata who lived to save others and didn't care about himself. That's the substance for their ship.

Castoria is complete different, and ironically she is the same mirror of Guda, as both were normal people who got thrown into position of a Saviour. Guda applied on a work on observatory and certainly didn't expect to become a field commader in a war against ancient demon. But since every other Master is dead, he have no choice, but to carry that mission, because no one can. Castoria was normal girl who should become Saviour according to prophecy, and she doesn't really wants to be one and scared about that, but still goes, because no one else could.

You may dislike Guda as much as you want, and say that it makes no sense for Servants to like "bland soulless cardboard", and for many instances of fanservice My Room lines you even would be probably right, because they like him solely because he's protagonist.
But for Castoria it actually makes thematic sense.

Kirsch x Caenis is also falls under this concept of story actually. I saw some people saying that was "new version of Fate route".

Meanwhile Muramasa is nothing of that, he is just old japanese blacksmith with admiration for swords, who got summoned by a villain, but isn't really enthusiastic about working for her, because he is not evil, so he doesn't mind helping good guys.

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This is how Nasu lost his soul. If he had to write LB6 back in the time, he would make actual nice Guda x Castoria story instead of the moronic plot with Muramasa shipping.

Anyway, it's just 16 hours till the LB6.2, and I don't want to read the story about Caster Artoria being taken away by blacksmith. I just took all of the drugs that I have had, I hope I will cease to exists before LB6.2 starts.

Thanks to Merem guy specifically, since this avatar was real nice and gives feeling of true Type-Moon soul.