So I spoken to the lady at the inn in Morthal for work and she told me that the Jarls men left a bounty to slay a giant at stonehill bluff . I travel to the location and successfully killed the giant. An arrow appeared on my compass where I then started to follow it. Instead of it leading me to the appropriate NPC it lead me to http://www.uesp.net/wiki/Skyrim:Pacturin stonehills. From what I know of this NPC has no connections with politics. He works for Bryling by running the rockwallow mine in Stonehills. So why did it lead me to this man to collect the bounty?

If you side with the Stormcloaks then Sorli the Builder (Pactur's wife) will replace Idgrod as Jarl of Morthal. I'd guess its something to do with that.

I guess this may explain that. I ran into the same exact situation and did indeed side with the Stormcloaks.

I did sided with the stormcloaks and Sorli was given Jarl status however I thought she becomes her own steward? Shouldn't I had came to her for the reward, and not her husband? I also told Sorli about Falion's secret place that he goes too and since then shes appears to ignore her duty as Jarl to stalk him none stop... even go as far as staying at his house.

Idgrod will stalk Falion too if you do that quest for her. Must be something in the water around Morthal (besides mudcrabs).
Did Pactur pay you the reward? If so hes doing the job even if he doesn't have the title.

Yeah he paid me 100 gold (Thought it was a tad cheap for fighting a giant).