Going through wizarding life as The Boy Who Lived has been wearing on our
intrepid hero. After the events chronicled in the five books (defeated
Voldemort as a baby, defeated him again as a firstie, defeated his
memory in second year, defeated him AGAIN in fourth year, threw off his
possession in fifth year, blah blah blah), the wizarding community once
more looked to him as a symbol of hope against the mounting forces of
The Dark Lord. Harry resented this attention and the responsibilities
that came with it, but his innate sense of justice and freedom prompted
him to contribute as much as he could (or was allowed) to the resistance
efforts spearheaded by the Order of the Phoenix.
Ultimately, it wasn't much. The war had taken on a much broader scope beyond
England, and much of the battles took place in arenas far from Harry's
location. The dread and fear that it caused, however, was pervasive.
Fewer and fewer students returned to the school with each successive
holiday, either scared off from the wizarding world, or kept at home by
worried parents. While Harry himself still preferred being at Hogwarts
than with his Muggle relatives, he felt that the emphasis on keeping him
safe (and therefore away from anything remotely resembling fun) was
excessive.
He got together with Ginny Weasley at the end of his sixth year, but it wasn't
anything like the blushing innocence of a first relationship; this was
the darker connection of two people trying to stave off the horror of
the outside world by any means possible. Though he often told Ginny in
the course of their relationship that he wished they could have had a
more conventional courtship, she never seemed to mind. She was, in the
end, the one who saved his life.
It was near the end of Harry's last year at Hogwarts that the Dark Lord decided
he was going to attack the school himself. Dumbledore's Army, still headed
by Harry, had been preparing for this possibility, but because the
Ministry had been expecting an attack on Ministry headquarters, there
was little by way of Auror protection. Even when reinforcements came,
the battle was ugly. Eventually, Harry found himself herded away from
the main battle, accompanied only by Ginny. That was when Voldemort
showed up. Already exhausted from his defence of the school, Harry fell
again and again to Voldemort's attacks - to the point where it certainly
looked like the Dark Lord was going to win...when Ginny Weasley fell to
her knees and begged for Harry's life.
Voldemort, who had some vague reminiscence of Ginny from his memory's encounter
with her, was only too glad to momentarily turn his attention away from
Harry to torture her. It was this vivid depiction of debasement of an
innocent at the evil wizard's hands that spurred Harry to crawl for his
wand and cast that most unforgivable of Unforgivables, Avada Kedavra, on
his life-long nemesis. Unfortunately, he couldn't get Ginny out in time.
She was destroyed too. That event turned the tide of war, though.
Without their leader, the Death Eaters were cast into confusion and
chaos, and made easy pickings for the Dumbledore-led attack. And Harry
was credited for a victory he doesn't feel he deserves.
Harry is both physically and emotionally exhausted from his encounter with
Voldemort, and guilt-ridden over Ginny's death. Moreover he's terrified
that his ability to cast an Unforgivable means that the darkness that
he'd always suspected to be lurking in him might take him over and that
he might become the next Voldemort.
"He who fights with monsters might take care lest he thereby become a monster."
- Friedrich Nietzsche