@Zael Maybe she also has a reason to be there, we know nothing of her and also from most of the other kids, from that sneak peek page it seems that su has some weird healing powers.
@ixsaz, still doesn't make sense to add to the workload of the healer senselessly, as well as cutting short the effective time you can resist (ie. buy time for others, which I believe was very much the goal there). As for the characters being suicidal, well.. :|