Breeding for fear

[Nils]

]A question: is it possible that Eru created Ainur in a way that they were unable to breed, because he feared that some of them would become powerful beyond all control? Just a thought...

And thou, Melkor, shalt see that no theme may be played that hath not its uttermost source in me, not can any alter the music in my despite. For he that attempteth this shall prove but mine instrument in the devising of things more wonderful, which he himself hath not imagined.

Actually, I'm pretty sure that Melkor twisted elves so they become orcs.

According to the Silmarillion (Elvish Myth), you'd be correct. Even so, how did Melkor twist the Elves? The breeding theory could be a way of 'twisting'.

If Melkor could just change hroar, then why didn't he just go out and turn all those who opposed him into slugs and throw them into a giant bowl of salt?