The Silmarillion/Fridge

Fridge Brilliance

 * When Thingol heard about the massacre of his kin (the Teleri) by the Noldor, he banned the speaking of their language (Quenya) throughout Beleriand. This meant that the Noldor (whom he no longer trusted) had to speak in a language he and his people could understand, or risk being shunned. It also meant that, while he could not demand that the Noldor get rid of the swords that had killed his kin (since they were needed in the war against Morgoth), he could still punish them by banning the language in which the orders to kill the Teleri were given.
 * Meta-example: The Silmarillion itself was compiled from Tolkien's notes, many of which were not entirely consistent with one another... just like different versions of real-world mythology.

Fridge Horror

 * In The Silmarillion, the Dark Lord Morgoth imprisons Hurin and forces him to watch from afar his family be destroyed by Morgoth's curse. Among other misfortunes, Hurin's two surviving children unknowingly marry and conceive a child. Just how much did Morgoth show Hurin, exactly? It makes it even more amazing that Hurin never screamed once.