Despite not being of the Chaos persuasion, nor having read much of the fluff, I found this explanation of Abaddon’s motivation and back story interesting – especially as he seems to come in for a lot of flakk from the fanboys:
http://aarondembskibowden.wordpress.com/2013/08/22/lets-talk-about-abaddon/
Hmm, might read some more of the Black Library books after all…
Of course Logan could take him with one arm behind his back!
Hammertime 40K 
Pretty good read! I don’t normally read ADB’s blog but what I’ve read from it is pretty interesting.
What I was told about the Horus Heresy novels is to read the first 3 in order, then skip around as you like. The 4th book, Flight of the Eisenstein, is alright, it’s definitely in chronological order but not necessary. Basically ADB and Abnett are the 2 best authors in the Black Library, the rest are either passable or just bad. I don’t know how the guys that wrote the 2nd and 3rd books in the HH are rated, but by the time I finished Flight of the Eisenstein I was a bit tired of the writing style that is probably meant to appeal to teenage boys.
The book I lent you, the Eisenhorn omnibus, is not about Space Marines at all, it’s about an Inquisitor but is very well done. I plan to read Ravenor, a related series, next – I’ve heard a lot of bad stuff about most of the Black Library stuff and will probably stick only to Abnett, ADB and only the most highly-rated authors. The one I have about the Grey Knights, The Emperor’s Gift, is interesting though, if only to give a bit of background of how a company of Space Marines operates before and after combat.