Boromir was the heir power of Gondor. Together, he and Aragorn represented Men in the Fellowship. Boromir was a mighty fighter, and extremely proud and courageous. He was also under the pressure of a kingdom constantly under attack. Boromir succumbs to the temptation of the Ring, attempting to seize it forcibly from Frodo, helping to set in motion a series of events that resulted in the breaking of the Fellowship and ultimately, his own death. Despite his crime of trying to steal the ring, Boromir made up for it by valiantly defending Merry and Pippin, at the cost of his own life, later confessing to and being forgiven by Aragorn, and was remembered as a hero by the rest of the Fellowship.
Boromir was above all else exceedingly valiant and steadfast, and was held in great esteem by the fighting men of many nations. He was noted as being somewhat dissimilar in manner and thought from both his father, Denethor, and his brother Faramir, but he loved them both greatly.
He was selfless and bold, but he took little interest in the books and scrolls that his brother so often read, having little interest in lore. It was said of him by Éomer that he had a great deal in common with the people of Rohan. However, his desire to protect his people, and his inability to do so, left him vulnerable to the predations of the One Ring. This eventually caused him to attempt to take it from Frodo, though he deeply regretted this almost immediately after it occurred. At one point, when envisioning he would have hoped to achieve if he took the One Ring and overthrew Sauron, his world after Sauron's defeat was one of peace and security, where he used the Ring to rule with wisdom and generosity.