He's has a few reasons to hold back trust. The first person he met up with other than Losties (Danelle) strapped him to a bed and sent electric curent through him. Ben lied to him and the tailies A.L. shot his woman and tied him to a tree. I would be a bit wary of people I didn't know really well too. Besides Desmond is a bit freaky right now.

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Hope is a very dangerous thing to lose. - Sayid

I do what my Rice Krispies tell me to. - Anonymous