Everyone you see in your dreams you've seen in your life before.
Only if you've only seen them once.
Your mind bends and morphs images you've seen before, thus forming dreams.
Think about how you never actually see yourself die in dreams.
That's because you've never actually died yourself, so your mind can't create that image.
It can set it up like you're going to, but you wake up before.
I've always found this so fascinating.