Hi Sandy,
What my INTP enjoys in books is very wide ranging, but hope this helps:
1. Graphic novels:
a) The Sandman series by Neil Gaiman, the dark humour, multi-threaded storylines and illustrations gives sufficent details yet room for imagination... Actually, most books by Gaiman. Snow, Glass, Apples is pretty nice too - a darker retelling of Snow White.
b) If he enjoys LOTR, you could consider getting The Hobbit, by the same author. If you think the above graphic novel idea will work, it is available in full colour illustration too.
2. Stories/Books by Yasunari Kawabata (or if you'd prefer, a collection of Japanese short stories by different authors)
The Izu Dancer and other short stories for e.g. - The japanese aesthetic of nuanced prose and intense but suppressed emotions, layered imagery, and overall search for beauty and identity running through the stories could be an attractive read.
3. Schott's Original Miscellany
This is a cute book with a collection of entirely random facts ranging from the twelve labours of Hercules, to some Shakespearian insults to palindromes.
4. Oscar Wilde's short stories / The Picture of Dorian Gray.
5. Faerie tales by Grimm, but written in their original form, where it is much darker, and the punishments harsher, and less happy-ever-afters.
Other authors on her shelf include Kerouac and other Beat poets. Vonnegut, Terry Pratchett are sometimes around. There's a book jointly written by Gaiman and Pratchett the name of which slips me now...
hope this helps,
I was scared nobody would be able to help me! 
