I ordered the drinking buddy back to sanctuary and he made it there but he just chills out back behind the main building and thd quest won't complete. Thoughts?

Thats not where you were supposed to send him for the quest. Though I always keep him >.> myself.

I don't think the quest technically completes until you sell it to Rufus. Keeping it for yourself is optional, but that doesn't cancel out the option of selling it to Rufus.