One of the biggest themes in the Lord of the Rings trilogy is the connection of love, and how it binds the characters to one another, no matter how their journey cross and part ways. This can be seen with Aragorn and Arwen, who love each other no matter the distance and time they must spend apart; with Sam and Frodo, who stay together right to the very end despite Frodo trying to leave his friend behind; and with Gandalf and the fellowship, because he manages to find his way back to them, even after he gives his life defending them from the attack of the Balrog.
But possibly one of the most tragic relationships in the trilogy, one that is full of both love and pain, admiration and belittling, brief joys and great sorrows, is that of Faramir and his older brother Borormir. There are lots of extended scenes in the movies in which viewers see the bond between the two being tested by their cruel father, and his constant championing of one and degrading of the other. Yet throughout it all, they stay loyal, and their souls stay intertwined, long after Boromir dies protecting the hobbits from the Uruk-hai.
In fact, they are so linked that Faramir is persuaded to trust Frodo and Sam when he finds them sneaking through the lands with Gollum as their guide. Despite the terrible things that have been done to his people by the enemy, and despite his duty to protect Gondor from all trespassers, he trusts the hobbits purely on the basis that they knew his brother. He is of course keen to hear all that he can of their adventures with him, of the events that passed since the fellowship set out from Rivendell, and of what transpired to bring his noble and mighty brother to his end. Unfortunately, Boromir’s death comes as a shock to the two hobbits, who had already parted ways with the others by the time that the tragic demise occurred. However, they are still able to prove that they did, in fact, travel with him, because they are able to name the horn of Gondor when Faramir asks them to tell them something of significance about his brother.
Once he has confirmed that they were friends, Faramir tells the two hobbits of a strange occurrence that he had on the banks of the river whilst he was out guarding one night: "I saw, or it seemed that I saw, a boat floating on the water, glimmering grey […]" He goes on to describe the ship, mentioning that there was nobody steering it, and that it was surrounded by a strange light. Inside the boat, he says, he saw the body of his brother Boromir, recognizing his gear and his face, but noting that his horn was gone.
Faramir recounts that he called out to his brother, asking about the horn's location and where Boromir was bound. But there was no answer, and then: "The boat turned into the stream and passed, glimmering on into the night." Both in the books, and in Peter Jackson’s film adaptations, it is really difficult to tell if this is a real encounter that Faramir has, or a vision sent by the powerful beings of Middle Earth, to warn him that more danger is on the way. He even describes the scene as dreamlike, and yet he knew he was not dreaming because he did not wake up. After this event, there was no doubt in Faramir's mind that his brother was dead.
There are lots of things about this that make it seem ethereal, rather than a physical bodily experience, from the description of the "pale light" around the boat, the fact that it disappears so quickly, and the fact that it felt so disorientating and other-worldly to the poor younger brother. Of course, this could have been the shock of seeing his brother’s body making him feel light-headed and detached, but it could also be because his soul is linked to Boromir's. This link awarded Faramir the rare privilege of being allowed to watch it depart from Middle Earth forever. This especially makes sense in the films, because Boromir’s body, and the boat it rests in, can be seen falling over the edge of a massive waterfall, which would have crushed the boat and given Boromir’s body to the sea, rather than transporting it to Faramir’s side.
The loss of his brother, and knowing that he died because of the evil temptation of the ring after trying to take it from Frodo by force, is a huge sway in Faramir’s decision to let the two hobbits go, even though he is mistrusting of Gollum. This detail especially makes it feel as if the vision was sent to him for a reason. This vision would ensure that when the time came, he would be able to let the evil object and its bearer go, rather than taking it to Gondor where it would have had disastrous consequences for the fate of Middle Earth.