I come bearing a fanfic recommendation, just don't let the title fool you:
Lost Chronicles of Narnia: The Beast of Witherby Summary: Movieverse, AU, Just another "The Pevensies don't leave" fic. Summary: Caught between political positioning and shadowed enemies, five young monarchs attempt to unite two ancient foes in harmony.
Pairing: SusanxCaspian
Of all the CaspianxSusan fanfics I've read this is the one that had me refreshing the page over and over again in hopes of it being updated, it's already up to 5 chapters and it only gets better and better.
It has all the elements of a good read. A good plot filled with political machinations, a hidden enemy, the Pevensies in full splendour, and of course CaspianxSusan. The Caspian and Susan in this fic is just beautiful that you'll have to read the fic to feel it.
Don't miss reading this one if your a fan of CaspianxSusan!