Lyric discussion by rodddxl102 

Cover art for Immortals lyrics by Fall Out Boy

There is some depth here that hasn’t been identified.

“I try to picture me without out you but I can’t” - Painful reality. Obviously saying it is painful to think about losing someone we love, so we simply don’t think about it.

“Cause we could be immortals” - Content fantasy. Since we never ponder losing those we love, we have made them and ourselves immortal in our own mind.

“Just not for long” - painful reality. It is inevitable that we will lose those we love.

“And live with me forever now” - content fantasy. Back to avoiding the pain of knowing you will lose someone you love and the mindset that the current condition will last forever.

“You pull the blackout curtains down” - Painful reality. This is the moment when the loved one has actually passed. That which you have denied in your own mind has come to be.

“Just not for long” - content fantasy. Even after reality sets in, the mind pleads for it not to be true and you try to convince yourself it isn’t real.

In summary, these lines taken together in rapid succession as in the song emotes what happens to us when we lose a loved one. An emotional turmoil going back and forth between remembering contentment and what we took for granted at the time vs the pain of the immediate loss and not wanting to accept it.