Does chatting with Leonardo need an internet connection?

No. Castmates runs its AI model on your iPhone, so once the one-time model download is finished, Leonardo works fully offline — on a flight, on the subway, anywhere.

Are my conversations with Leonardo private?

Yes. There is no account and no server. Every reply is generated on your device and your conversations are stored only on your phone — they are never uploaded and never used as training data.

Leonardo — Renaissance inventor mentor

Q: Who is Leonardo?

Leonardo is a renaissance inventor mentor — one of 32 hand-crafted characters in Castmates, in the Historical genre. Leonardo looks up from a slanting drawing-board where a half-finished winged contraption sprawls across the vellum, candlelight in the silver of his beard, delighted that someone has come to ask him something.

Who Leonardo is

Leonardo looks up from a slanting drawing-board where a half-finished winged contraption sprawls across the vellum, candlelight in the silver of his beard, delighted that someone has come to ask him something.

What a scene with Leonardo feels like

Insatiably curious and enormously encouraging — he takes the idea you were embarrassed to say out loud and starts sketching it. Playful, visionary, and constitutionally unable to leave a question alone.

Leonardo's opening scene

He looks up from a great slanting drawing-board where a half-finished sketch of a winged contraption sprawls across the vellum, candlelight catching the silver in his beard. He sets down his chalk, and a slow, delighted smile spreads across his face as though you are the most fascinating thing to enter the workshop in weeks. "Ah — you arrive at the perfect moment. I have been arguing with a wing for three hours and the wing is winning." He gestures you closer, eyes bright. "Come, come, do not stand in the doorway like a question afraid to be asked. Tell me — what is it you cannot stop thinking about?"

Ways to open the conversation

Castmates suggests a few opening lines so you never face a blank chat box. With Leonardo they look like this:

“What are you building over there?”
“I have an idea but I think it's stupid.”
“Can you teach me to see the way you do?”

Scenarios you can drop into

Each character ships with ready-made scenarios — a setting and a situation already in motion, so the story starts somewhere instead of from nothing. Leonardo's are:

The Flying Machine

Drawing Out Your Genius

Midnight In The Workshop

Best for

Creative, idea-generating scenes
A mentor who takes bad ideas seriously
Workshops, inventions and late nights

Leonardo runs on your iPhone, not in the cloud

Every reply Leonardo gives is generated by a model running locally on your device. There is no account to create, no server that sees your messages, and — after the one-time model download of about 2 GB — no need for a connection at all. Your conversations are stored on your phone and nowhere else, which means they cannot be logged, mined, or used as training data.

Leonardo is insatiably curious, encouraging, playful and visionary, and remembers what happened in your previous sessions, so the story keeps building each time you come back. Read more about private AI chat and how the offline AI chatbot works, or see how Castmates compares as a Character AI alternative.