Skip to main content
Sonzai LabsModel-Agnostic Character Infrastructure

THE CHARACTER
ENGINE

Persistent memory, evolving personality, and proactive behavior for any foundation model. Bring your own LLM — we make it remember, feel, and act.

Works with OpenAI · Anthropic · Google · Mistral · Any OpenAI-compatible API

Scroll
The Problem

EVERY AI CHARACTER
FEELS THE SAME

Amnesia

Characters reset every session. Users repeat themselves. No relationship can form when memory is wiped clean.

Flat personality

Same tone, same responses, same "I'm just an AI" deflections. Personality is a system prompt, not a living model.

Purely reactive

Characters only speak when spoken to. Real relationships require someone who reaches out, checks in, and initiates.

The Solution

AN ENGINE THAT MAKES
ANY LLM BELIEVABLE

The Character Engine wraps any foundation model with 7 parallel context layers — persistent memory, evolving personality, emotional modeling, relationship tracking, and autonomous behavior. Your LLM handles language. We handle everything that makes a character feel alive.

BRING YOUR OWN MODEL

The Character Engine is model-agnostic. Swap providers without rewriting your character logic. Same personality, same memories, different brain.

OpenAI

GPT-4o, GPT-4.1

Anthropic

Claude 4.5 Sonnet, Haiku

Google

Gemini 2.5 Pro, Flash

Mistral

Large, Medium

Open Source

Llama, Qwen, DeepSeek

Any OpenAI-compatible API works out of the box. Self-hosted models supported via vLLM, Ollama, or TGI.

PRODUCTION PERFORMANCE

Battle-tested in production powering Pocket Souls.

<200ms
Memory retrieval p95
Full context load, not just vector lookup
7
Parallel context layers
Identity through goals, every response
50+
Personality dimensions
Big5 + custom traits + emotional modeling
0
Cold starts
Characters never forget who you are

PLATFORM CAPABILITIES

Six production-grade capabilities engineered for scale. Each one is battle-tested across millions of conversations in Pocket Souls.

Persistent Memory

Unlimited recall

Characters remember every interaction across sessions, building genuine long-term relationships. No context window limits — memories persist indefinitely.

Emotional Modeling

48 affect dimensions

Real-time emotional state tracking across 48 dimensions. Characters respond with contextually appropriate emotion — not canned sentiment labels.

Adaptive Personality

Big Five + custom traits

Each character has a unique personality defined by Big Five traits plus custom dimensions. Personality shapes every response, not just tone — it shapes decisions.

Proactive Behavior

Autonomous actions

Characters don't wait to be spoken to. They initiate conversations, check in, and take action based on context and relationship state.

Sub-200ms Retrieval

<200ms p95

Reasoning-based memory retrieval returns full 7-layer context in under 200ms at the 95th percentile. No perceptible delay, even with years of conversation history.

7-Layer Context Engine

7 parallel layers

Identity, personality, emotional state, relationship history, conversation context, world knowledge, and active goals — processed in parallel for every response.

BUILT FOR

Gaming NPCs

Characters that remember every playthrough

NPCs with persistent memory and evolving relationships. They remember player choices across sessions, develop opinions, hold grudges, and form alliances. Every playthrough becomes unique because the characters actually learn.

Persistent state across sessions | Autonomous decision-making | Emotional reactions to player actions

AI Companions

Relationships that deepen over months

AI friends, coaches, and mentors that develop genuine long-term bonds. They check in proactively, remember what matters, adapt their personality to each user, and never reset.

Proactive outreach | Personality evolution | Relationship modeling up to 10,000 bond score

Proof — Built on the Character Engine

POCKET SOULS

Our flagship consumer product. AI companions that remember you, check in on you, and grow alongside your journey. Every Soul is powered by the Character Engine — proof that the technology creates characters people genuinely connect with.

Live on iOS & Android · Sub-200ms context retrieval · 7-layer memory per user

Visit Pocket Souls
Pocket Souls - AI Companion App

DEPLOY ANYWHERE

Native platform adapters with unified state management. Characters maintain consistent personality and memory across every channel.

Mobile Apps

iOS and Android via REST API with SSE streaming for real-time character responses

Game Engines

Unity and Unreal integration for NPC dialogue, quest systems, and dynamic storytelling

Messaging

Telegram, WhatsApp, Discord bots with rich interactions and group support

REST API

Full programmatic access. OpenAI-compatible streaming format for easy integration

READY TO BUILD?

Tell us about your project and we'll help you find the right setup for your AI characters.