If you're sandwiched between two people, an intimidating giant [change to: any object representing your greatest fear] facing you, and the back, (anybody, could be a harmless baby). Who would you want to remove, given you can only remove one?

Think the standard (or rather, universal) answer would be "the person behind", for we all hate uncertainty. (even if the person behind could be a baby. BUT it could be a man with a knife as well.. but well, it could be a harmless baby...).

There is also the intimidating giant [or any object representing your greatest fear] in front of you which could represent confrontation, something most want to avoid.

If the chances of the person behind being harmful is only 30%, would the results be different? If it's reduced to 20%? 10%?

(Still, I think I'd pick the choice of removing whoever's at the back)