“ “Uwooooooooooooooooooooooooooooooooooooooooooooohhh!!!!!!!!” ”
The roar of the two overlapped.
The Level 0 charged in to where his fist could reach his opponent.
Accelerator raised one of his black wings.
The two attacks flew past each other, and the Level 0’s attack hit only an instant
earlier. Accelerator’s face got blown backwards, and he lost his balance. The
black wing’s path got diverted slightly, and missed the Level 0 by millimeters.

[...]
From inside Accelerator’s heart, something black surged out.
It was not directed towards the Level 0, but towards something more indistinct.
The hatred and anger towards this illogical and unreasonable world burst out in
the form of words.
“Why!! Why didn’t anyone save that brat!! Aren’t you a hero! The hero that
stopped that ‘Experiment’ with only one fist!! Then go save her! If you can do
what no one else can, then you can definitely save that brat!!”
Accompanying the roar, an even larger power surged through the black wings.
At the same time, something that was crumbling in his heart started to fall to
pieces.
He could no longer stop.
Even the action of remembering Last Order’s smile could no longer stop the
violence.
“It’s ridiculous that a villain who was no better than a piece of shit like me was
guarding her!! No matter how you think about it something must have been
wrong!! How could I possibly be a hero!! No matter what, I can only choose the
blood-stained path!! Why do I have to do all these things!! If a hero like you had
shown up earlier, then something like this mix-up of position wouldn’t have
happened!! That brat would not had to have suffered as much this way!!”
While the two exchanged blows between fist and wings, the Level 0 probably
didn’t know why it had turned out this way either. Accelerator himself probably
didn’t know what he wanted to say; it was just air passing through his lips, no
one else should be able to understand him.
Instantly, both of them went silent.

[...]
“(He should be dead now… it’s impossible for him not to be.)”
Accelerator thought.
It was impossible for that not to be the case.
Even so,
“Why…”
Accelerator let out a sound that was almost like a groan.
In the end it turned into a mighty roar.
“Why couldn’t a hero like you just die?! If you die, then everything can finally
break apaaaaaaaaaaart!!!!!!!!!!!!”
He heard the reply.
Right in front of him, the teenager that clenched the blood-covered fist spoke:
“… things like heroes are unnecessary.”
Footsteps rang out on the snow.
Fist and wings collided.
The air shook, many attacks impacted, and blood flew out

[...]
“(That last attack…)”
Accelerator gulped.
“(Even the weakest of those attacks hold destructive power that isn’t possibly
something a human body can handle, right?!!)”
Those things didn’t matter.
The source of his terror was not those superfluous theories.
What was most important right now was ‘the most terrifying enemy’ closing in.
At this time, Accelerator remembered something.
Before, in the cargo holding area fighting the Sisters during the ‘Experiment’,
the same kind of clash had happened.
Wasn’t the most terrifying thing about that teenager being that he never gave up,
and stood with his own two feet under circumstances where that could not
possibly happen?
“Just choose already…”
The Level 0, just like back then in the blood-covered cargo holding area, charged
towards the Academy City’s strongest esper. “Do you want to keep protecting
with your hands? Or do you want to give it all to someone else and run away? Or
do you want me to give you a hand in choosing!!”
That fist,
Clenched to the point where it couldn’t get any tighter.
“Whether it be pride or whatever, for whatever can make you hold your chest up
high, just choose already!!”
A roar exploded out.
The sound of the Level 0’s fist struck surely onto Accelerator’s face.
After stepping onto the path of ‘Evil’, the power gained after many coincidences,
the black wings do not work against that teenager.
No,
Actually,
The thought of that it is necessary to step onto the path of ‘Evil’, was that only a
shackle? No matter what, what he had to protect at any cost was Last Order’s
smile. This had nothing to do with where she was located. If someone truly
wanted to protect her, it didn’t matter if he himself was ‘Good’ or ‘Evil’, he
didn’t even have to surpass people like Kakine.
The kind of person whose shadow he had been chasing all this time was
probably an existence like this. It was not because of ‘Good’ or ‘Evil’. And it
was because Accelerator didn’t consider this, that the ‘pure Evil’ Accelerator
could not reach him. If that was the case…
Accelerator thought even as he fell backwards.
The fantasy that had occupied his heart for all this time had shattered.
To Aru Majutsu no Index Volume 20 Chapter 4 Part 6