Is Mercy Possible for All?

I'd like to actually argue for one of the points in the last posts, one which I've seen come up even more often than the others and which I myself have felt the force of at one time. This is the point that mercy, in order to be mercy, cannot be obligated, that the definition of mercy is something that one shouldn't get but does (and, by extension, to something that some don't get, but that one does). I've already posted my questions concerning the parallel notion of justice.

First, let us imagine a world in which God does actually forgive all sinners. We can say for the time being that this is not a necessary world, but either (if one likes counterfactuals of creaturely freedom) that God would create such a world, or that (otherwise) that is simply how an actual world will turn out. Now, let us imagine a world in which God forgives all but one sinner. Has the status of God's action hanged at all towards the rest? How can God's refusal of one sinner affect whether or not God had mercy on others?

Now, if this is true in the actual world, then why should that forgiveness of God towards beings in this actual world be affected by what God could have possibly done had God created a different world? Has God been merciful toward us based on the fact that God could have not been such? There seems to be no reason to think that modality has any influence on the mercifulness of an action (though, how would this tie in to discussions of libertarian free will? Would the same apply? Or is any action for the good, such as mercy, is fine whether or not it is determined, but any evil action can only carry moral responsibility if libertarianly free?).

I'm not sure about the analogy to possible worlds; coming from a classical theist standpoint, I think that there would also be other reasons to deny God's necessary obligation (though not God's actual obligations). This runs into the problem of how God's acts relate to God's nature, though. Perhaps one could say that any specific obligation can have come about or not come about, but that whatever one did obtain would be indicative of God's nature (so, there would be certain obligations that could not have come about, such as damning all those God has promised to save). Also, God is infinite and creation can only be finite, so creation must always only reveal a finite portion of God's nature, thus affecting what obligations may or may not come about. Or, perhaps we can say that what we really care about is God's identity rather than God's nature, and so it doesn't matter what God could have done; we just don't live in those possible worlds.

At any rate, the first argument (about this world) seems to be much more compelling, and is all the universalist would need to challenge some dominant notions, like that of Strange's; God can have mercy on all without this having any bearing on the quality of the mercy. I don't see why the notion of grace should fare any differently.

So, that takes care of necessitation (or at least universalization) aspect, unless I can hear some good reasons otherwise. The other notion is that mercy is undeserved. Is this to say that when I come across a starving, homeless person on the street that I happen to be in a perfect position to help, and decide to care for her, that either (a) my action is not merciful, or (b) that (barring other possible conflicting commitments) I have no obligation whatsoever to help her? Perhaps I could say that I have no obligation toward any one person, but I must help someone. As I don't have the way out of saying that it is because I must show my nature (and so therefore am ultimately only obligated to myself in whatever way I please), this action would be obligatory and yet merciful.

This also shows how mercy and justice are compatible, and really two expressions of the same attribute. Which fits much better with divine simplicity (God doesn't have to worry within Himself over how to reconcile the two!), and also seems to fit the Biblical model better (What does the Lord require of you? To do justly, to love mercy, and the walk humbly with your God), which does not seem to see any problem with the two.