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Guide · updated 2026-10-29

How to keep AI characters consistent

AI characters stay consistent when every shot starts from the same reference images and the same written description. Make a reference sheet (front, three-quarter, full body), attach it to every image and video prompt, paste one fixed description, and add a lock line that tells the model to keep the face, hair and costume exactly the same.
Mara reference: frontMara reference: turned 45 degreesMara reference: full body

Step 1: make a reference sheet

Generate three images of your character in Nano Banana Pro on a plain background: front, turned 45 degrees, and full body. These become your character's ID card.

Step 2: write one fixed description

Describe only what is visible: age, hair, one distinguishing mark, and the costume piece by piece. Paste it word for word into every prompt; changing even one word invites drift.

Step 3: attach the references every time

In Google Flow, add the reference images as ingredients for every new image. For video, start Veo 3.1 from an approved still that already has the right face.

Step 4: use a lock line

Keep exactly the same face, hair and costume as the reference image. Keep everything else the same: the light, colours and framing.

Step 5: fix, don't re-roll

If one detail is wrong, edit that detail with the lock line instead of generating a new image. Re-rolls bring new drift.

Why does the face change after a few clips?

Each clip that starts from the end of the previous one copies small errors forward. Start each video clip from an approved keyframe instead of chaining clips.

Written by Asad Syal, founder of Join AI Film Academy.

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