My god, that was outstanding! What a brilliant, brilliant fic. Your Lucius is one of the most wonderful things ever, and I'm in love with the wonderful two-tier plot, past and present. Regulus' desire to live was painful to watch, if not quite as painful as Lucius' reaction to Narcissa's death. That *hurt*.
The smut was very nicely done and hot (especially the neat way of bringing Lucius out of shock), and I loved that Narcissa was fully integrated into things, and that it remained clear always who was the most important person in Lucius' life (not usually a het person, but having a *very* soft spot for L/N).
Another gorgeous thing was how the pace sped up when Lucius makes his way into the Ministry, and everybody's response (especially Harry's!) to the perceived threat and to not knowing what he was after.
You made me tear up at the end, which is a rare thing, and the ending gave the story a lovely feeling of, well, peace and a new beginning even though it's the end. It made me think of Dumbledore's next great adventure, and I'd wish it on those four.
An exceptional read! There are two people I could imagine having written this (well, I'm lousy at guessing, but...), so I'm dead curious for the reveals now.