General Reccommendations
A wholeheartedly unrecommended fic, <a href='http://www.fanfiction.net/s/7106346/1/For_His_Own_Sake' target='_blank' rel='nofollow'>Good God, man, cut it out with all the bashing!</a> While that's not the actual title, that's seriously what the whole fic is. It started out with a decent premise that Keitaro leaves because he's fed up with it (with little to no bashing and angst, despite the genre tags), but then comes the bashing. And Bashing, and bashing, and bashing. It's like, "Are you quite done yet? I want to get on with the fucking STORY." The past 5 chapters have seemingly been the same thing repeated over and over again.
I want to see what Keitaro is up to. Not see more bashing. While I'm not against a little bashing at times, the author takes this way too far.
Anyway, a fic I actually recommend is <a href='http://www.fanfiction.net/s/5364366/1/Parallel_Lives' target='_blank' rel='nofollow'>Parallel Lives</a>, a Shinobu and Keitaro-based fic. After giving his confession to Naru, and waiting for nearly a month for her reply, getting depressed, Shinobu finds out what's wrong, and convinces him to go on a vacation to get away from everything. And begs to come along. Since no one could say no to those puppy-dog eyes, he gives in, with Su running background interference.
Definitely one of the better Keitaro/Shinobu fics out there, and their relationship is actually believable. Unlike some *coughNarucough*