A story that completely brought me into the K/S fandom, and which is on comparatively few rec lists, is 'Veritas', by theproblematique (all of her writing is fabulous and there is a lot on her work on LJ that isn't posted on AO3).
Also, even if you don't usually read TOS, there is this stunning story which talks to the heart of any K/S shipper (and you can put your own voices to it, as it is mainly comprised of messages which are increasingly honest exchanges, between Kirk & Spock, when they are torn apart by duty, time and space and... then...OMG!) Anyway, PLEASE give it a go, people, 'Communication' by Jenna Hilary Sinclair:
no subject
http://archiveofourown.org/works/1141066/chapters/2308617
Also, even if you don't usually read TOS, there is this stunning story which talks to the heart of any K/S shipper (and you can put your own voices to it, as it is mainly comprised of messages which are increasingly honest exchanges, between Kirk & Spock, when they are torn apart by duty, time and space and... then...OMG!) Anyway, PLEASE give it a go, people, 'Communication' by Jenna Hilary Sinclair:
http://www.ksarchive.com/viewstory.php?sid=1306&warning=1
:-)