Five minutes. Jeremy remained completely petrified for five whole minutes with nothing to say, nothing to feel... nothing to think. The unending fear of getting caught absolutely crippled him; even though the possibility of her being a purist was astronomically low, she was still undoubtedly just a regular person. Magic was but fiction to them, and she just saw a spell in person. She had every right to be shaking or fearful.
Since that wasn't enough to calm him down, though, the next bit was. If she were a purist, he'd already be dead right now. She would have taken advantage of him while he was stunned, but the fear that still slipped out of her voice meant he was still safe. A purist wouldn't be afraid of something like an ice spike, but a regular person like her? Her reaction was normal... for Rena, at least. Jeremy let out a sigh, still shaken up. There was no way he could avoid telling her the truth now.
"You can't tell anyone about this," he firmly declared as he stood up. "Look, I know you're confused, shocked, maybe even afraid, but... please just listen. I'll explain it all."
At that, Jeremy removed his glasses and pocketed them before swiping his hair back.
"What if I told you magic was real?" he asked, walking to the other side of the table. "Would you believe me? Well, heh, you just saw me use it, so that's a moot point. Still, before then, I wouldn't blame you if you didn't." Jeremy got on his knees and put his hands together over the table; the same chilled air began misting off of his hands. "It's not that people can't use magic," he began, slowly pulling his hands apart to reveal the head of a rose formed out of ice. but rather... those who can are hunted and persecuted."
As he uttered the the last few words, the ice began to scatter into the air in several, infinitesimally small particles. "Why?" he asked in a knowing tone as he looked up to meet her eyes. "There are people who are fearful of the changes magic would bring to humanity- another faction of people who can use magic who resent it at the same time. They call themselves "Necessarius", or purists, and hunt down magic users like animals if they don't affiliate with them," he explained before growing a more remorseful look on his face.
"My parents were murdered when I was still young. I was adopted by a friend of my father's who sympathizes with our cause, and I've had to live out my life in fear as an outcast under a new name." Jeremy stood from his crouching position, averting his eyes. He never imagined he'd be telling any of this to Rena or anybody, and it wasn't even his intent to go on for so long. He hoped she didn't end up even more confused, but writing the ice spike off as just some freak accident? Impossible. He had to explain. The two were alone, though. The thought of killing her might have crossed his mind if the two weren't so close, but that just wasn't the case.
"Look, Rena... I care about you a lot. I'm not telling you this to get you involved; you don't want to live my life. I'm only stressing how important it is that you don't tell anyone, and I wouldn't do that if I didn't completely trust you."