Writing People Off / In

Have you ever written somebody off? I'm talking about that person in your life or past that blew it or failed you or didn't come through when you really needed them to or didn't live up to expectations, etc.~and now just the mention of their name gets you thinking, "Oh yeah, that loser." And we run into them all the time. People who other people have written off. People who~they're a "loser" and they know it and they can't seem to forget it or shake the feeling because others, quite frankly, have refused to let it go. The bottom line about relationships is people are gonna mess up (except us?). The solution isn't writing them off. I'm not talking about bucking up, playing like you weren't hurt or stuffing your feelings. But then again maybe I am just a little. And what might things be like if we chose to write people in instead?