Quote Originally Posted by Kraco
So, this is something like missing a wasp that had bothered you for hours when it's finally gone, just because it had become a part of your life, eh? I don't know how it was in the manga, but in the anime Shikamaru clearly didn't like smoking, and it would be beyond odd for him to start to smoke just to remember Asuma better. He was always the logical fellow, thinking before acting and analysing even feelings. Unless he would have made a conscious break from that core aspect of his personality, it would have been a personality breach.

Unless it's some psychological mumbo jumbo of him "becoming" Asuma for the duration of this revenge trip. Well, I guess that could be it, and it could even work.
That's what made it so powerful. He admits it with the first one he smokes that he hates cigarettes but he keeps doing it in the next chapters because it's a tribute and a way for him to remember his fallen master.

And don't give me that, the most analytical of all would still break down to an insane revenge-hungry numskull after having his father figure killed in front of him. If anything we should be impressed that shikamaru actually came up with a plan before setting out to take out akatsuki.