Interfaces used to be screens. Now they're characters.
They talk, listen and remember. People don't just use them, they get to know them. Who they become is a design decision.
On screen: Teletubbies · Doctor Who
Clients: Particle6 · Moonbug · Vessa.ai · EmotionMachine.ai
- 1,600+ live conversations with an AI actress, in 30+ languages, with 0 user safety incidents
- 81 personas from one architecture, each tested to hold
- 1k+ beta users for a WhatsApp concierge with one consistent voice
- 25 years creating characters across live, interactive, virtual and TV
"Jeremiah is a rare specialist — fast, perceptive, and a joy to work with."
"Jeremiah's insights helped us sharpen our character-driven approach and clarify our positioning. Clear, actionable, and fast."
"Jeremiah brought real depth to our early explorations of AI characters. His work on modular prompts and evaluation scaffolding meaningfully informed our platform."
Character turns a product into a relationship.
Users don't develop a relationship with features. Design a product as a clear character and it becomes easier to use, easier to trust and worth coming back to.
Trust
People test the edges of anything that talks back. A clear character knows what it will and won't do, and holds under pressure.
How Tilly launched safely →Affinity
People remember who they talked to, not which feature they used. Character carries the brand into every reply.
Vessa's concierge →Stickiness
People come back to someone, not something. Someone who remembers your name, what you said last time, and sounds the same every time.
Structuring 81 personas →Selected work →
Talking Tilly
An AI actress, live with the world's press and public. 68 days from voice lock to launch.
Vessa.ai
When the character is the product.
EmotionMachine
81 distinct personas from one architecture.
Multi-coach
Five coaches, one voice. Why they felt the same.
Fan character
A mascot that talks back, all year.
One architect. The whole stack.
I work across the full character build, from first sketch to live operations.
- 01Strategywhat it's for and how it pays
- 02Characterpersonality, values, rules
- 03Voice & facehow it sounds, looks and moves
- 04Brainsystem prompt, knowledge, guardrails
- 05Safetycare built into the system
- 06Platformvendors, evals, versions
- 07Launchpress, access, rollout
- 08Live opsreview, data, the next build