-Harry Potter and the Half-Blood Prince
-The Da Vinci Code
-The Devil Wears Prada
-Harry Potter and the Deathly Hallows
For me the answer is obvious: it's that theme of discovering someone indirectly, "studying" their personality. I guess I love this theme because I'm guilty of doing similar stuff in real life (well, online; real as in not fictional), I stalk comments more than almost anyone can imagine. So it's cool when there are epic/legitimate reasons for this (in these examples: the person you're "studying" is the enemy/left you some clues before getting killed (2x)/simply is your boss).
So, did my ramble make you think of any books? No problem if they're very different from those I mentioned, in fact that's great! The books I've listed are obviously quite different from one another as well!
Also, please don't feel like a creep if you don't know me but happen to see this, or if we haven't talked for ages or whatever. If you have something to say, I'm happy to listen!!!
Many thanks in advance:)