Why does oberon want the changeling boy and why does Titania?

The first mention of the changeling boy is Puck who
says,

For
Oberon is passing fell and wroth

Because that she, as her
attendant, hath

A lovely changeling boy stol'n from an
Indian king.

She never had so sweet a
changeling:

And jealous Oberon would have the
child

Knight of his train to
trace the forests
wild.

Titania is the next to
talk about him when she refuses to give him to Oberon.   Speaking about the boy's
mother, she say, "...her womb then rich with my young
squire,..."

Oberon is the last
to make a heraldic reference when he say, "I'll make her render up her
page to me."

It would appear
from these references that Puck is referring to the future of the changeling boy, to be
knight.

Titania it would seem is referring to the next step
for the young boy's progression toward knighthood, that of being a squire where the
young boy leaves the company of women to learn the skills necessary to become a
knight.

Oberon is referring to his current position as a
page since pages were the first step in becoming a knight and they would attend the
women and learn the gentle arts from them.

It would appear
that Oberon wants the changeling boy because it is time for him to leave the world of
women and join the world of men.