How does Borachio change during the course of Shakespeare's Much Ado About Nothing ?

One change we witness in Borachio is that he becomes
repentant and remorseful for his deeds by the end of the play.

When we
first meet Borachio, we see that he is as depraved a character as Don John. We see him
act as a spy for Don John, reporting that Claudio intends to marry Hero and that he
overheard Claudio and the prince agree that the prince will court Hero on Claudio's
behalf and give her to Claudio. Borachio tells Don John this with the hopes that they
can use it to double-cross both Claudio and the prince, as we see in Don John's lines
concerning Claudio, "That young start-up hath all the glory of my overthrow. If I can
cross him any way, I bless myself every way" (I.iii.55-57).

First
Borachio and Don John try to trick Claudio into believing that Don Pedro has broken his
word and is actually courting Hero for himself. But, when the results of that ruse do
not last long, Borachio comes up with the plan to seduce Margaret into appearing in
Hero's bedroom window with Borachio while he calls her by Hero's name, leading Claudio
to publicly shame the real Hero. However, when Borachio learns that Hero has died from
the shock of her accusations, Borachio feels extremely remorseful, believing that he
deserves to die for his wrongdoing, as we see in his
lines:

My
villainy they have upon record, which I had rather seal with my death than repeat over
to my shame. The lady is dead upon mine and my master's false accusation; and briefly, I
desire nothing but the reward of a villain.
(V.i.228-232)

Hence, we see
that while Borachio started out to be as depraved a character as Don John, wanting only
to serve Don John's own selfish gains, Borachio later becomes remorseful. He repents his
actions, blames himself and Don John for Hero's death, and wishes to be punished by
death for his villainy.