Sinister is a very dark, twisted, and at times unpredictable horror film. Almost every scene makes you feel apart of the movie. From the very beginning, we see there is already a problem with the house itself. Ellison Oswalt's 7-year old daughter Ashley says she dislikes the house and Ellison makes a deal with her - if he dislikes the house, they would move back to their old house. This is a foreshadowing of what would happen later.
Ellison Oswalt is hellbent on solving the mysterious murder cases of a suspected serial killer throughout the film but what begins as a pursuit of justice turns into an unhealthy obsession. His book on crime was a side project.
If you take notice, he becomes distant from his family and preoccupied with his police work. He becomes less concerned about his family's safety and wellbeing. It was until he and his wife hit a breaking point where his wife made him refocus his attention on his family vs. his book.
His daughter and son show signs of Bagul or the villain of the film but Ellison Oswalt is too blind to realize it. Ellison Oswalt constantly tries to find clues as to who the suspect could be. Little does he know that Bugal had already influenced his children.
At the film's ending, we realize that his daughter Ashley already succumbed to Bagul's influence leading to the whole family's death. Bagul was looking for the perfect candidate to be his ideal daughter. Ashley unlike the other children was such a grand artist and connected well with Bagul. The morale of the story is that when parents fail to spend time with their children, there will always be a malevolent entity who will. Ellison Oswalt realizes too late that his self-centered obsession with fame consumed him and his fate was sealed when Ashley said "Don't worry daddy, i'll make you famous.."