Nelson was thrown into disarray when the summon appeared. He always knew that mentally and emotionally unstable people are dangerous summoners. But never did he see a student who could actually call out a demon from the abyss.
He promptly threw into action as his student and her summon engaged in a fight. Normally he would just let it be and only watch, as it is normal procedure in taming a summon. But this time it's a precarious situation for her and everyone in the room.
Demon summons are tricky summons to call. Their minds are so complex that perhaps humans who summon them will never understand them.
One is that regardless of how satisfied they are with the offerings their service is to be exchanged with, they will try to kill their summoner at first sight. Afterwards they are loyal to their summoner who survives their fight to death in accordance to whatever rule that compels them to do so. Obsessive and sticky they are after each contract.
