Dreaming of Dead People

Last night I dreamt of a dead classmate. I always wake up from these dreams as if I struggled up from the bottom of the ocean, usually because the dream is so vivid. What adds to it is the fact that there is usually some lucid dreaming going on, not to mention the fact that it's a little scary to see a dead person while you sleep.
The reason why I ponder over this particular dream is that at the end I asked "How are you still alive if you're dead?". His answer was "I'm alive because you want me to be alive". This was startling, because I had lost touch with him before he died. And I wondered if mildly suicidal people could be kept alive because someone wanted them to be alive. Certainly each time I tried to kill myself, there was someone who wanted me to be alive more than anything, which probably made it harder to leave this earth. I also started to wonder if he had been bipolar as well. He had definitely had his share of depression and suicidal attempts, but he was also confusing. Some days he was withdrawn and cold, other days he was overly vivacious, and yet other days he was just normal. Given his age at the time that I knew him, it seems entirely possible...and yet it's taken almost 10 years to realize this...