Good idea to befriend the enemy?

If someone threatens you - they didn't do anything to you directly bad, but you feel weary around them, as in you suspect that they may turn against you. Is it best to try to 'befriend them'? Not become best friends or anything, I don't want to be totally fake, but just be on at least friendly acquaintance terms with them, so that you keep your @ss covered so to speak...is it wise to do this, or should I not go there?