If evil is a necessity (for the purpose of growth and development), where is the freewill in individuals choosing to be evil, sadistic, sociopathic, or psychopathic?

This is of course assuming that there is no such thing as an outside Creator.

  Maybe the creation or existence of freewill, is what led to the creation of "evil" or that which is not Source like in nature? 

   Source wouldn't necessarily have to create very different states in a structure for this to happen. 

  An analogy is, say you're born into just whiteness, that's all that you perceive on the outside of you.  But, close your eyes and go within, you could imagine something different than whiteness despite never having perceived it outside of  yourself.  You could at least wonder if there was more than just whiteness.

  It's not a good analogy, because it's more related to states of feeling/awareness, and starting to think thoughts or feel things different than the ones you first were aware of (because those were linked to your origins), and in focusing on the differences, you start to feel more disconnected from your origin and start manifesting that which is different from the origins. 

   After awhile of this, you may even manifest some very lacking in light states and perceptions, where love is almost completely absent, but fear, very separative thoughts/feelings, etc become dominant. 

  Welcome to the jungle that some of our siblings temporarily manifested and which some of us came into to retrieve those getting more and more stuck in same.   

The truth is, some of us who originally came in to help, to retrieve, allowed ourselves to get overly influenced and started to become stuck some too.   But like in all things, there are degrees.  Degrees of love, degrees of stuckness, etc. 

  Whether or not getting stuck to begin with, was something desired the Source or ultimately helpful in nature, is in my mind debatable. 

  However, in any case, the trick is to turn lemons into lemonades.