If anyone is into fanfics, I would recommend "Hayate x Vivio Files", it was a collaborative work by several authors. It started as a crack pairing, obviously, but it quickly got a serious overtone, and it succeed marvellously. The three stories you should start off with (that is, if you decide to read it) are written by deathcurse (the originator of the series), and are, in order how you should read them: firstly, "You Never Lose By Loving"; secondly, "Lose By Holding Back"; and thirdly, "Prerogative of the Brave". After that, you can read the remaining fics in pretty much any order you want. Those are, by deathcurse: "Gut Feeling", "Little Girl", "Ulterior Motives", "It Must Be Love", and "Judgment Day".
Also, part of the series: "To Let Nature Run its Course" by Extrinsical, "Grandmama Wolf" by RadiantBeam, "No Atheists in Foxholes" by DezoPenguin, "The Things We Tame" by Shigan (this last one is listed on deathcurse's profile as 'in progress', but it is actually completed).
In all, some 82 000 words worth of fics (42 000 of which are "Prerogative of the Brave"), and these are some of the best fanfic writers in the Nanoha fanbase. It is also possible that in the meantime some other authors have contributed as well, there have been some years since I read this particular series.