He says that there is a vacancy in Percy's household, owing to one of his esquires being made a knight, and a page has been promoted to an esquireship.

He said that he spoke to Hotspur, before he went south, anent the matter; and asked him to enroll you, not exactly as a page, but as one who, from his knowledge of the border, would be a safe and trusty messenger to send, in case of need.

As he has served the Percys for thirty years, and for ten has been the captain of their men-at-arms; and has never asked for aught, either for himself or his relations, Percy gave him a favourable answer; and said that if, on his return, he would present you to him, and he found that you were a lad of manners that would be suitable for a member of his household, he would grant his request; partly, too, because my father and myself had always been stanch men, and ready at all times to join his banner, when summoned, and to fight doughtily.

So there seems a good chance of preferment for you.
"Your mother is willing that you should go.

She says, and truly enough, that if you stay here it will be but to engage, as I and my forebears have done, in constant feuds with the Scots; harrying and being harried, never knowing, when we lie down to rest, but that we may be woke up by the battle shout of the Bairds; and leaving behind us, when we die, no more than we took from our fathers.
"I know not how your own thoughts may run in the matter, Oswald, but methinks that there is much in what she says; though, for myself, I wish for nothing better than what I am accustomed to.