Since Chris referred to St. Gregory's take on this yesterday, it seemed good to put up a few more of his words on the topic:
Shall I ask to whom went the blood which Christ shed forth?
If to the wicked on - alas, Christ's blood for him who is evil!
But if to God - why, when we were under another's power?
For it's always to one who holds power that a ransom is paid.
The truth is this: he offered himself to God,
so as to snatch us from him who had us in his power,
so that, in exchange for him who fell, he might take
the Christ: but he who christens cannot be caught.
This is our opinion. We respect, however, the typologies.
The sum of it is this: worship the Trinity. (Poem 1.1.10, De Incarnatione, adversus Apollinarium)