Oddly enough, Carion's Scottish ending differs from the original French version. Although the father is still taken to prison in the latter (because like, you really can't just torture and kill people, regardless of the circumstance), the broken French family appears to make far more optimistic amends. In other words, while the original ends on a relative high note, the remake clearly does not, bringing the notion of the film as a vehicle or platform for character study into even starker relief.
In the penultimate scene of "My Son," the camerawork — namely, which parent the camera chooses to pull into focus — appears to take its lead from McAvoy's actions, which determine the tone of the film's ending. While the original's Guillaume Canet read the scene (wherein father, mother, and son are reunited after having narrowly escaped death) as a suggestion that the estranged pair have a potential future, McAvoy does not. In fact, his prison-bound Murray appears to have long since let that dream die, and it's hard not to retrospectively view the scene with Frank's cell phone videos as that dream's proverbial coffin nail.
The actor's decision to see Murray's final scene with his son and ex-wife as both an apology and a goodbye directly affects the cinematographic mechanics that follow. The father's continual recession into background blur mimics the inconsistent and intangible presence he has in his son's life — even after nearly losing him. That the two versions of the film would end on such disparate notes is further proof that Carion genuinely is taking his cue from the improvisations of his leads, even as they endeavor to take their cues from Carion's set-ups and their co-stars' behaviors.
