This is so cool. I especially like your take on the idea of bookworms. The ending took my breath away. I've been sitting here for five minutes, trying to recover from how awesome that was. Very original and well written. Just brilliant.

Edits:
‘Santi noticed some gaps between the books as he walked. (The) gaps marked the places where books had gone missing.’ Using ‘some books’ twice just makes it seem a little repetitive.

‘Seeing the gaps left behind by the missing books annoyed Santi, but they (were) the least of his worries.’

‘The puddle grew larger, chasing the librarian (as) he retreated…’

I didn't write down all the little things, but I would suggest going through it again to see if you can catch a couple little mistakes. Other than that, I really enjoyed reading your entry. I wish you good luck.

Good work. I really like it!

Crywolf Chronicles, indeed! Excellent insertion, my friend.
I am very fond of this series. There is something rather Brother Caedfell-like about Santi and his library that lends itself to the short-story format, and the Santi-Tony interactions are fricking adorable. As to using the Welsh, it would be awesome to include the translations at the end, rather than leaving your reader to look them up - although these days any translation is as close as your keyboard.
Favorite line: "I didn't creep. I simply moved to stand directly behind you so I could watch you for long minutes at a time without you being aware of my presence."
Fixes: The little typos you'll catch yourself, next time through, but the paragraph in which 'gap' appears four times in close proximity could use your attention.

The secret life of books, as told through the lens of Augie-humour.
It's a fun read, plenty of good ideas: living books/alchemy/bookworms in human form. Actually I kind of want to know more about that last one...
And I never knew Cortana was a sword...
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Rydw i ddim yn siarad Cymraeg :(