First of all, don't be put off by either the summary or the MPreg aspects of this story. I,
the first recommender, don't generally like MPreg and steer away from lemons, but FroggyFran weaves those elements into such a compelling story that they don't matter in the long run. The characters are spot-on; Prussia's character is slightly toned down from its canon portrayal, but it gels perfectly with the dark atmosphere of the story and never comes off as OOC. Even better, Russia is given the depth fanfic often denys him: He's not a monster, but an overgrown almost-child hurt by his past, who loves Prussia and his children and wants them all to love him in return. Germany, Italy and even the Baltics are given their own depth as well even though they have less "screentime". Focus is also placed on Russia's close relationships with the Romanovs, Germany and Prussia's brotherly bond, and the weird dynamic between Lithuania and Russia, and all those relationships create scenes that made the person who didn't cry over Fry's dog get teary and choked up.
I really can't recommend this story enough, even for people who aren't fans of Russia/Prussia, ratings above PG-13, or MPreg.