Random House Webster Unabridged Dictionary has nine different definitions of the word pain. The third one is the one I'm interested about: mental or emotional suffering or torment. Pain is one of those emotions, when related it creates into your interlocutor a feeling of empathy. However regardless of much descriptive one can be about their experience of a painful situation, pain remains as intimate and personal with oneself as is the experience of sex. When you think you're alone, its quiet presence reminds you of otherwise, it stares at you and you have no other choice but to stare back. When you share it with other people, it sits at a corner of a room, listens to you and when the people are gone, it comes and sits at the center and challenges you. It's a feeling of helplessness close to depression but not quite, a feeling of hopelessness close to dejection but not quite. It results from the impossibleness of controlling a situation and the worst of pains is the one that one did not choose to face, the one with the source close to your heart, close to a definition of oneself. The process of that feeling is unique to each individual, but common to all is the solitariness that all must face in the experience of it.
If pain was a color, it'd be black and red: Black to represent darkness, sadness, unhappiness; Red to represent: vivacity, stridency, authenticity (people can fake their joy, their happiness but not their pain or sorrowfulness).
If pain was a choice between God and the Devil, I'd probably choose God - God because He claims to be author of everything, including pain.
If pain was a medication, it'd be the "Nivaquine" - Bitter in the mouth and the stomach but strengthening the immune system.
If pain was a coding tool, it'd a compiler - no need to explain.
If pain was an institution, it'd be school - a hassle in itself but a mind sharpener, a character builder.