Do I need to say how much I like this? :^)  As in very, very much like it?

Annatar and Celebrimbor's individual voices and dialog are great. Love the remarks about the lanterns in Nargothrond.  The interaction of these two craftsmen rings true to the common ground that scientists and engineers, who may be strangers to one another, can so quickly find.

...designing everything from better forges to better mousetraps.

Yes, the practical things first and then...lower the boom.

Well done, Aiwen!

A good glimpse at the beginning of the professional relationship between Annatar and Celebrimbor!   Too bad at how it will turn out in the end. 

I liked these parts a lot: "It was much more useful than hiding away in Valinor...Celebrimbor never had seen why they should all have to live in poverty because they had the misfortune to live in the wrong place..."

...Annatar smiled. "Oh yes, it is important to show solidarity. On the other hand, I can quite appreciate your desire to automate that function as much as possible!"

"...No matter how many I made, they always wanted more. I got so sick of making them in the end that I broke Feanorian secrecy and taught other people how to make them." My father did not speak to me for nearly two months after that.  (LOL!)

I like your character of Celebrimbor, so very Feanorian yet tempered, just like the Celebrimbor in the Silm who "repudiates his father," recognizing that the people of Nargothrond have a right to his family's secret knowledge for aiding them as refugees. This is a really nice detail and shows so much of what I think makes Celebrimbor a fascinating (and tragic) character.

The last paragraph is a simply fantastic ending!

Here on the recomendation of Pandemonium - I like this. I like that Sauron gains Celembimbor's trust by offering to help him make things better. I like that Celebrimbor isn't depicted as being rebellious against the Valar for rebellion's sake, but because darn it, everyone deserves the advantages of certain technology - and I like that your Annatar doesn't come across as entirely evil, but with a bit of moral ambiguity. I enjoyed this!

I very much like this! Aquaducts, water-mills... an instant rapport between your protagonists... Excellent :D

So Celebrimbor broke the Feanorian I.P. guidelines, hunh? *Grins gleefully*

 I'm glad to see you are writing more. I very much look forward to seeing it!

I can see that first meeting occuring like this.  Celebrimbor is so eager to work with someone who can teach him; he's used to being the authority and he wants to know more, it's sad.  And perhaps Annatar is regretting the waste even as he contemplates using Celebrimbor and then destroying him.  Nicely done.

Poor Celebrimbor.  So well-meaning, so fair-minded, so curious and forward-looking - and so doomed.  You do a nice job here of showing how Sauron uses all the man's best qualities to lure him into his trap.