If you're basing this comment on the initial call GZ made to the police then you're misconstruing what happened..perhaps intentionally.
As to why Martin would return and confront GZ a few minutes later, the answer seems obvious. A better question might be, if Martin were afraid for his safety why did he return at all?
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A) Obvious? Please tell us exactly what was in Trayvon's mind after he ran away from the stranger who followed both in a car and on foot.
B) What is the name of the eyewitness who says that he saw Martin return? Please provide that detail.