"That was pretty much what happened..." Neville let out a long breath. "After I entered the 'Fourteenth Path,' everything went smoothly. It wasn't like at the beginning, when I felt it was very hard to get through."
"Mr. Lovegood, what's happening to Neville?" Alice Longbottom's voice was filled with urgency. "He's already past the age for a Magical Outburst..."
She thought back to the scene she had seen in Beauty Sephirot. "Could it be an Obscurus? I heard that if young wizards reject magic, they can produce an Obscurus."
Vizet snapped his fingers, and a large mass of Obscurus, pitch-black like mist, emerged and floated above his palm. "Neville, can you touch it? Or sense its existence?"
Neville asked no questions. He simply rolled up his sleeve and reached out, trying to grab the Obscurus into his hand.
His attempt failed. The Obscurus truly was like mist, scattering away from the hand that swept through it before gathering back together again.
"No..." He tried a few more times, then shook his head and said, "It's like air. I can't feel anything at all..."
Frank Longbottom realized something, and a flash of surprise crossed his eyes. "Mr. Lovegood, could this be an Obscurus? But this appearance..."
"Yes, I'm an Obscurial." Vizet clenched his hand into a fist, and the Obscurus returned to his body. "But I've already completely tamed the Obscurus, so its appearance is somewhat different."
"If it were another Obscurial, they could sense the Obscurus I released this way... Since Neville can't feel it at all, that means he isn't an Obscurial. Please don't worry."
This was a method for detecting Obscurials that he had developed through studying the mural rubbings Newt Scamander had given him;
After the Statute of Secrecy was enacted, Obscurials were almost impossible to find