Celes felt the demons vile touch, like tendrils of corruption the demons influence crawled along the barriers of her mind. She had tracked it down to its layer deep within the woods of Harvendown. Now as she stood within the entrance of its lair she could sense its frustration, unable to overcome her physically it was now assaulting her mentally with a fury of a cornered beast. At each turn it had tested the barriers of her mind, and now it assaulted them in earnest.
The mental battled seemed like hours, but in truth no more than a few minutes had passed in the world. Her mental barriers were weakening, and as the demon felt her barriers breaking its assault only grew in intensity. Suddenly her barriers gave out, and the demon hungrily poured itself into her mind ready to find all of her doubts, sin, pleasures and… nothing. There was nothing. Celes' mind was a complete void, until suddenly it burned with a fury of pure hatred. As Celes poured all of her hatred for the demon and its kind she tempered it with a discipline obtained only by the most learned of Demon Hunters, forging her hatred into burning chains that wrapped about the Demons, mental form.

Show me… Everything!Her mind's eye burned brighter as she directed her hatred like a spear directly into the mind of the demon, ripping all the memories from it, before shattering the demons very being.

After returning to the Order Celes had locked herself within her sanctum. She had learned, costly as the lesson was that demon memories are just as dangerous as those who thought them. Celes did not trust anything she uncovered within them, but the demons main area of focus gave Celes enough of a lead to track down further demon activity and halt it.
The Order was impressed with her results at stopping demon activity, but even so she knew that would never approve of the method. As far as the Order was concerned once a demon had gotten inside your mind you was lost.
Celes was different; she had no emotions, but the hatred for demons. She wanted for nothing, but to hunt demons, and while her hatred threatened to consume her while she was younger, her discipline now rivalled the masters of the Order.

You shouldn't be doing that you know, one day you will find a demon that is too much, even for you.

'Shut up.'

Oh ho! Talking to me today then? Well this is a pleasant surprised, but still best to keep this conversation inside this pretty little mind of yours, some frown upon this kind of thing you know.

The Order did not create very social members, but with Celes' inability to feel emotions she had become somewhat of an outcast, and with her ability to trap demon minds she had further distanced herself with others of her kind. 'The Voice' as she had named it had spoken to her since she had awoken in the apothecary, the first thing it had done was warn her that she must not tell anyone about it, she had learned the truth of this the hard way, asking one of the members about voices in your head had made them fear that she was. The Order had tested her, but found nothing.
She had never brought it up again, and while she tried often to avoid talking to The Voice, the need to talk to someone, or something sometimes bypassed her better judgement.

Oh now you're just going to ignore me huh? Well fine! But you're gonna need a friend soon… real soon…

What do you mean?