Real Time
by Lawrence Watt-Evans
An unnamed time-travel guard is trapped in the 20th century and must keep ever vigilant
against those who might tamper with the time line because you never know whether the time
guard will be able to handle it all.
They might send someone else, but they might not. The tampering might have already
changed things too much.
“Real Time” by Lawrence Watt-Evans, in
Asimovs’s Science Fiction, January 1989.