I would say, "I already gave you two chances. Betray me once, shame on you. Betray me twice, shame on me. Betray me three times, well, there's not gonna be a third time. I only give two chances. My game's not baseball. You're out if you get two strikes."
I would hang back and see if he truly changed. If he didn't change at all, I would not let him into my life. If he changed, I'd give him a chance. I believe that everyone is capable of change.
I'm like ChinooksRock83. I believe that everyone is capable of change. If I saw that she truly changed, I would give her a chance. If I didn't, I would not give her a chance.
I Would Like To Say Something Like That I Will Accept And Together We Would Unite Against Another Common Enemy. Just Like Rivals Do In So Many Series But Since That Clearly Is Not Going To Happen...
If it seems genuine, I'd want to take things slowly and develop our friendship over time. I believe everyone deserves a second chance.
If I find out later that the person doesn't genuinely want to be my friend and talks shit about me behind my back, then f*** them.