SampeaStories
A long time ago, I readed 'Hetalia 23.5' for the very first time (and was freaked out). Then, I discovered KyoKyo866's incredibly touching and yet, disgusting 'sequel' to it : http://kyokyo866.deviantart.com/art/Regret-Chapter-1-326898896
I was at one point on the verge of tears when I listened to Michael Crawford's rendition of 'Baby Mine'. After reading Chapter 7 of 'Regret', I was really inspired and looked up to the german version of 'Baby Mine' : http://www.youtube.com/watch?v=jGMcfqe2pCM
And I just thought: 'Wow. It's perfect. What if, before Italy dies, he asks Germany to sing him a lullaby (to help him through being emptied of his organs)?
You really need to read the ''Regret'' fanfiction mentionned above to understand these two songfics.
And there you have it!