Roam

Not to be confused with King Rhoam, a character from Breath of the Wild

Roam is a character featured in the by Shotaro Ishinomori. Referred to in one of the chapters as "The Mystery Knight," Roam is a descendant of a master archer from the ranks of the Knights of Hyrule. When Roam discovered that Agahnim was sending the Seven Maidens to the Dark World, he sought after them  through the Portal near Death Mountain. Roam considers Link to be immature, stubborn and lacking discipline to wield the Master Sword, with Roam boasting that the Book of Mudora supports him instead as the hero who will save Hyrule.

It is stated in the comic that the Dark World changes the shape of its inhabitants based on their hearts, and a  person can only maintain human form by controlling their emotions. Thus, when Roam enters battle, he transforms into a humanoid eagle. Contrary to Link, who suppresses his transformation (shown to be a wolf-like creature), Roam considers his transformation an advantage and willingly lets his emotions change him during battle. Roam wields a sword when fighting as an eagle but can also be seen using a crossbow.

Biography
Roam first appears to challenge Link for the right to wield the Master Sword, He transforms into an eagle and proceeds to attack Link, who counters Roam's attack and defeats him. Roam apologizes for having misjudged Link and reveals to him that the  ancient Book of Mudora tells that the one who corrupts the Golden Land   will be defeated with the Silver Arrow, the sacred item that Roam has been seeking. When Roam tells Link he is also a descendant of the Knights of Hyrule, Link is overjoyed and begins to think that the two of them can join forces to find Princess Zelda. Roam is shocked to hear Zelda has been transported to the Dark World,  saying Link is too much of a "weakling" to wield the Master Sword and   save the princess. The young hero tries to defend himself by saying he has the three Pendants of Virtue to prove his worth, but Roam is unimpressed by Link's lack of discipline and immaturity, and begins to walk away to continue searching for the Silver Arrow. Before disappearing, Roam tells Link that he senses they will have to  join forces against Ganon, and advices the young hero to stay alive   until then.

Roam later reappears in ALttP:, arriving just in time to help Link defeat a three-headed dragon and save Princess Zelda. After they escape from Turtle Rock, Roam boasts that the Book of Mudora's prophecy supports him as the  Legendary Hero, for he is  the one seeking the Silver Arrow, and leaves to find it. However, Sahasrahla mentioned only a man who has overcome his own negative thoughts and emotions can  become the true hero. Since Roam has not, Link fears that this might  actually be his downfall even if he  finds the Silver Arrow. Later, when Link and Zelda arrive to Ganon's Tower, Roam suddenly appears and admits he has failed to find the arrows. Overwhelmed by his failure, Roam transforms into an eagle and flies up  to the  tower, worrying Link since Roam's emotions are out of control and  could  cause him to remain a beast forever. Zelda then asks for the aid of the maidens, which allows them to enter the pitch-dark tower. Inside, the group is attacked by illusions of Link's past foes, with a specter of Agahnim dangerously approaching Zelda. Roam quickly transforms into an eagle and attacks the illusion, although he loses his life dispatching the specter and saving Princess Zelda. With Ganon emerging from the illusion's remains, Zelda takes up Roam's crossbow as Link is trapped in between the trident. Zelda begins to ask for the aid of the maidens and fires an ordinary  arrow from the crossbow, but as it approaches Ganon, the power of the   maidens, Zelda, Link, and Roam, turn the arrow into the Silver Arrow, destroying the King of Thieves.

Trivia

 * Roam is based on 002 from Shotaro Ishinomori's popular manga , whose pre-cyborg name was Jet Link. Like Roam, 002 was able to fly.