JB laughed.
“Most people have that reaction,” he said. “That’s one of the reasons modern weapons aren’t allowed in the past. The first time travelers were spooked beyond belief by tracers, and it took a good decade for anyone to be sure what they were. Usually time travelers see duplicates—the real person, thrown off his rightful path, and the tracer. And that’s even eerier.”
Jonah tried to picture that. When JB came to the twenty-first century, had he been able to see tracers of Jonah and Katherine and Chip? Ghostly shadows doing whatever they would have been doing if JB weren’t there?
Then Jonah remembered that he and Chip wouldn’t have been in the twenty-first century in the first place if it hadn’t been for time travel. Where was Jonah’s tracer? What was his proper time period?
JB was still talking.
“We have a saying in time-travel circles, to explain the tracers,” he said. “‘Time knows how it’s supposed to flow.’ There’s a persistence in the very nature of time, always trying to get back to its original outcomes. …”
The ghostly tracer boys were done praying now and had climbed back up on the bed. The older one was looking at the younger one, his eyes serious and sad. And then the older one put his right hand in his left armpit and began pumping his left arm up and down.
“Is he doing what I think he’s doing?” Katherine asked.
“You mean, making fart noises?” Jonah said.
“Boys!” Katherine sniffed.
The younger boy on the bed began laughing silently. The older one did too.
He’s trying to cheer up his brother, Jonah thought. He must have known he was crying.
“I would have thought the fifteenth century would be full of chivalrous behavior,” Katherine fumed. “Knights and ladies and all that. Not boys acting as stupid as ever!”
“Oh, grow up, Katherine,” Jonah said.
Alex was ignoring them. He pushed past Katherine and stepped into the other room. He moved slowly, like each step might be risky. When he reached the bed, he lifted one hand and waved it first through the older tracer boy’s shoulder, then through the younger boy’s arm.
“Oh,” Alex said, his voice flooded with surprise. “That’s …” He turned back to the others. “Come and try something.”
Chip was already walking toward the tracer boys. Something about the way he moved made Jonah think of moths desperately flapping toward flame or—what was it, lemmings?—those creatures that would follow each other off a cliff. Jonah felt like he had to follow too, if only to protect Chip. Katherine lurched unsteadily beside him.
“Put your hand out,” Alex directed. “What does that feel like to you?”
It didn’t seem to have hurt Alex any, so Jonah obediently shoved his hand into both tracer boys’ chests.
He felt nothing. It was just like sticking his hand out into empty air. And the tracer boys didn’t seem to notice at all. Now they were shoving at each other, still laughing soundlessly.
“So?” Katherine said, having waved her hand through both tracers too.
“Don’t they feel different?” Alex said. “It’s like this one seems more … real.” He pointed to the younger boy, the one who had the same arched eyebrows and hooked nose as Alex.
“No, this one does,” Chip argued. He was standing beside the older boy, who had his right arm lifted in the air, emphasizing some point he was making to his younger brother. Jonah wished he could read lips, to tell exactly what the boy was saying.
But Chip wasn’t watching the boy’s face. He was extending his right arm to match the tracer boy’s right arm. Dreamily he spread his fingers so each one occupied the exact same space as the tracer boy’s fingers. Chip’s hand was bigger, his fingers longer, but that difference seemed to disappear as soon as the two hands joined.
“Whoa,” Chip said, a dazed look on his face.
Then he sat down, his legs overlapping the tracer boy’s legs, his chest leaning back into the tracer boy’s chest, his face melding with the tracer boy’s face.
Instantly the tracer boy stopped glowing.
And Chip disappeared.
FOUR
“Chip!” Katherine shrieked.
Chip’s face lurched forward, momentarily separating from the tracer boy’s.
“It’s okay,” he said. “Don’t worry. This is so cool!”
Then he leaned his head back, joining the tracer boy’s exact dimensions again.
Now Jonah saw that Chip hadn’t completely vanished. Jonah could still see, faintly, Chip’s blue jeans and Ohio State sweatshirt and Nikes, coexisting with the tracer boy’s black tunic and tights and elflike shoes. And in the boy’s blond curls Jonah could see the bristles of Chip’s shorter hair. Even Chip’s face seemed to be a mix of his own jubilant awe and the tracer boy’s more solemn expression. Jonah didn’t know how his eyes could see two different things in the exact same space at the exact same time, but they did.
“It’s like the mirrors,” Katherine whispered.
“Oh, yeah,” Jonah muttered. He knew exactly which mirrors she meant. One time when they were on vacation, their parents had taken them to a science museum that had a pair of special one-way mirrors rigged up, back to back, so two people could sit on either side and, by adjusting the lighting, see what their faces looked like blended together. Katherine had loved it, dragging total strangers over to sit opposite her. “So that’s what I would look like if I were African American. … That’s what I would look like Asian,” she kept saying. When their parents finally pulled her away, she was scheming: “When I fall in love and want to get married, I’m going to bring my boyfriend here so we can see what our kids will look like. …”