Hotspur is an proficient leader and a daring warrior, almost fit to be a prince. He is part of the Percy family of the North, which helped give Henry IV the rise to the thrown. King Henry respected Hotspur's bravery, valor, honor, and determination so much that he envied Northumberland for having such a son. At this moment in the play, King Henry's own son, Prince Hal, was going through a phase of rebellion. Hal pretends to be a vagrant by hanging out with Falstaff at the Boars Head Tavern. Even though he later transforms into a brave and valiant warrior, the King thought his son was nothing more than a dishonorable delinquent. Because Hal behaves this way, King Henry wishes a fairy would trade his own son for the son of Northumberland. Hotspur has more prince-like qualities than Prince Hal at this moment in time. Hotspur's relationship with Prince Hal has always been on a rival basis. In the play, they are relatively the same age and that means Hotspur can be a threat to future thrown that Hal wishes to inherit. Hotspur has experience in the battlefield and other characteristics that make him a worthy candidate for a prince. The king introduces the conflict that exists between the two men by describing how he would rather have Hotspur as a son.
"That some night-tripping fairy had exchanged
In cradle-clothes our children where they lay,
And called mine Percy, his Plantagenet!
Then would I have his Harry, and he mine" (I.i.86-89)
It is also significant that their given name is the same: Harry. This means that they are interchangeable in the eyes of the king.
Prince Hal's character is unlike...