Love is the greatest magic of all.
I really like the fact that J.K. Rowling used the above theme in
her books, and I believe that is one of the reasons why Harry
Potter is a global phenomenon.
Love, sacrifice, redemption ....
Some examples..
The love Snape has for Lily is what kept Harry safe, and enabled
the latter to finish the task of ridding Voldermort.
The love Narcissa Malfoy has for her son is what prevents Harry
from being hit by another Avada Kedavra, which will end his life
once and for all. And that love redeems the Malfoys.
The love Lily has for Harry, of course... that casts the rebound of
the killing curse.
The love Harry has for his friends, including Dobby, and that
enabled him to master Occlumency at last...
and countless other examples...