The Single-Use Per Target Rule
One Use Per Person · No Easy Second Draft
Lelouch can normally affect a person with his Geass only once. He cannot simply correct a bad order by commanding the same target again, so phrasing and preparation matter as much as raw power. Jeremiah's Geass Canceller later creates an important exception by erasing an existing effect and reopening possibilities Lelouch thought were closed.
Direct Line of Sight & Distance Bounds
Eye Contact · Reflections Work, Screens Do Not
Lelouch's command requires visual contact with the target's eyes. Glass and reflected eye contact can still carry the Geass, while a camera feed or television image cannot. The limitation is one reason Zero relies so heavily on masks, staged encounters, hidden observers, and battlefield positioning instead of treating Geass like a remote-control superpower.
Memory Loss & Command Duration
SPOILER!
Memory Gaps · Commands Can Outlive the Moment
People affected by Lelouch's Geass commonly lose awareness of what happened while the command controlled them, leaving suspicious gaps afterward. Some orders end as soon as the task is complete; others remain embedded for far longer. Suzaku's command to 'live' becomes the clearest example, repeatedly overriding his self-destructive instincts at moments when survival is otherwise the last thing he wants.