[Thirty minutes earlier]
"Drillv!" Professor Flameflicker calls out, causing thirty rouge freshmen to jump, as no one had seen her enter. A warforged raises his hand and chokes out, "Here? Um, are we taking role..."
"Elerk, Conroy?" "Here."
"Finnegan, Dellen?" "Here."
and other names.
"Rigel, Simon?" No answer. "Simon? Not... a good... sign."

[now]
Simon looks around the empty room. Briefly, he thinks he hears the echoey sound of someone yelling "Sneak attack!", but it fades quickly.
"Oh, so you're the one," someone says, and Simon finds a tall skeleton in an out-of-date letterman jacket and plaid pants, bone structure held in place by crackling green flame standing beside him. "Did you know you were three moments sideways from the timeline? It's really making me itch."

"Yeah, you're just a little to the right of 'now.' Cannot even begin to imagine how that happened. And I've seen a lot in my 1,540 years at this school."

"Well, that's the thing, isn't it?" the skeleton-person says. "Time is a river, but you're washed up on the banks. If we're too careless, you could be grabbed up by the rapids and smashed into some rocks. Figurative rocks. Possibly literal ones. Chrono-boulders are unpredictable."

"This... may have been my fault. I'll have to do some research into it. In the meantime, you'll find you can interact with things that are relatively stationary for long periods. But mobile things are going to be hard for you to perceive. Just... hope they don't start moving the furniture around."

"Cool. So if you need anything, just leave a note to Vance Van Wilder on the sill. I'll find it eventually, or... already. And I'll be there immediately."