Why do we dream what we dream?

I have crazy dreams all of the time. The other night I was chosen to be in the hunger games and I was trying to escape by shooting my miniature bow and arrow but they were little dart blades instead of arrows.  Then I finally got on the road in a car and I was dodging tornados but they were pixelated like from an old video game.  One major theory of where dreams come from is that they are just a random compilation of things that happen while you're awake, so let's see where this dream came from.
-I recently watched The Hunger Games
-I recently watched the TV show Arrow
-My fiancé bought an original Nintendo for the house (the one from 1985) so I've been playing a very pixilated Mario for a few days now
-I'm terrified of tornados and they often reoccur in my dreams

So after realizing that, my dream looks a little less scary to me.

Fun fact, we end up spending about 6 years of our life in dreams.  Some dreams are fun so that might be okay, but it turns out that for men and women 8 out of 10 dreams are caused by a negative event or emotion.  For example. after trauma people often experience nightmares.

Have you ever had something from the room you're sleeping in, like your alarm or a conversation, come into your dream? That is because while we are sleeping part of our minds are still conscious of what is happening around us and sometimes that slips into our dreams.  When I was a Freshman in high school there was an earthquake in my hometown.  And that night I had dream that I was about to get in the tanning bed and then there was an earthquake.  The next morning when people were talking about the earthquake I told them I felt it the evening before at the tanning bed, confusing my dream with reality.  They were confused telling me it happened sometime in the early morning, then I felt embarrassed, realizing that I hadn't felt the earthquake at the tanning bed, I felt the earthquake in my dream.

Sigmund Freud is one of the most well known psychologists.  He did a lot of research and theorizing about why people dream what they dream.  He published a book in 1900 called "The Interpretation of Dreams."  Freud thought that dreams were ways that we could satisfy our wishes.  He thought dreams were symbolic versions, known as manifest content, of our unconscious drives and wishes (latent content.)  Freud theorized that these are wishes that might be harmful if we express them directly, so instead we express them in dreams.  He thought that all humans had two basic drives: sex and aggression; and that dreams could almost all be traced back to hidden sexual or aggressive wishes.

There are other theories as to why we dream.  One theory is that dreaming helps us file away memories; brain scans have shown links between REM sleep and memory, lighting up the parts of the brain during REM sleep that also store memories.  So in this case, dreaming is just a random compilation of our day's experiences as the memories are filed away, which seems to be the case with my Hunger Games tornado dream.  Another theory is that dreams help develop and preserve natural pathways and that dreaming is providing a physiological function.  Dreaming could also just be a neural activation, where REM sleep triggers neural activating, evoking different random visual memories and then our sleeping brains weave them into stories.  Some psychologists think that dreaming is caused by cognitive development.  When we're  young, we see slideshows of pictures in our dreams, but as we get older our and our cognitive abilities grow, our dreams become more intricate.

Now that you've heard the theories, why do you think you dream what you dream?