Hell, the mere fact that the film ends with a battered and bruised John gently carrying an injured and unconscious Sam to safety in a Bridal Carry while she affectionately nuzzles his neck strongly implies that the two characters were originally intended as husband and wife in an earlier draft of the script, and the necessary re-editing to make them siblings was done pretty hastily. Furthermore, John and Sam's mutual character arc of overcoming their past estrangement following them having chosen different career paths is framed less like two siblings learning how to care about one another again and more like two embittered ex-spouses slowly falling back into love. Virtually every scene between the two characters implies a more romantic connection than a familial one, with their immature bickering when they first meet back up coming across as awkward flirting more than anything else.
Doom: This movie suffers from this trope to a near-comical extent regarding John and Samantha Grimm, a Brother�Sister Team of fraternal twins who are the film's primary protagonists and serve as The Not-Love Interest to one another.
