Choosing an AI model — Lyra University

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Choosing an AI model

Lyra ships a small, curated set of models, each tuned for storytelling. There is no overwhelming list to wade through — pick the one that fits the scene and switch any time.

The models

Mercury

Made for immersive roleplay — stays in character and brings scenes alive. The default.

Mars

Fast and reliable, with plenty of detail. A great everyday pick.

Saturn

Characters who do not just say yes — they push back, and make you earn it.

Neptune

A fan favorite — creative and keeps long stories on track. Available to everyone.

Venus

Long, richly written replies with a huge context — for readers who love prose.

Neptune Plus

Neptune at full strength — same creativity, full precision and noticeably faster.

Luna

Quick and sharp — snappy dialogue that keeps pace with you.

Jupiter

Ultra. Vast and patient, holds it all. Built for sprawling worlds and long, intricate stories. Lyra Pro includes a weekly allowance; on other plans each message costs stars.

Orion

Ultra. On Very long (subscribers), writes about 2x as long as Mercury — vivid, deeply in-character writing that holds a long story together. Stars on every plan.

Sirius

Ultra. On Very long (subscribers), writes about 2.5x as long as Mercury — our finest storyteller, rich, consistent, and true to every character. Stars on every plan.

Dynamic

A blend of models you tune — every reply is drawn from your mix.

Every AI model, one tap on its name in the message bar — switch per chat, any time.

Which should I pick?

Start with Mercury — it is the default, tuned for immersive roleplay that stays in character. Pick Mars for fast, detailed everyday replies, or Saturn when you want a cast with a spine — characters who push back instead of agreeing. Reach for Neptune when you want a more creative voice, or Neptune Plus for the same model at full precision and noticeably faster, or Luna for quick, snappy dialogue. Choose Jupiter when a story leans on a lot of history, a dense worldbook, or a long-running plot you do not want the model to lose track of. For the best writing we offer, pick Orion or Sirius (Ultra). Dynamic lets you blend several models so every reply is drawn from your own mix.

Switching models

Pick a model per chat by tapping its name in the message bar — it applies to the next reply. You can change it as often as you like; different scenes in the same world might suit different models.

Every model is available on every plan, and the picker shows each one's price. Every plan includes free roleplay on Mercury; depending on your account it is without a limit or a free allowance, then stars or a subscription. On the free plan, premium models cost stars for every message; Lyra+ and Pro include a weekly allowance first, then pay the same per message. Lyra Pro includes a weekly Jupiter allowance. Ultra models (Orion and Sirius) cost stars on every plan. On Jupiter, Orion and Sirius a long chat costs more per message, because each reply re-reads more of the story; the picker shows this chat's price and the steps ahead.

Tools keep your model

Turn on Tools under the ＋ beside the message box and the chat can use tools — same model, same character. Every model can drive them, so nothing switches and nothing changes hands: replies draw on the same weekly allowance your model always uses. When it ends, you may need to subscribe or upgrade to keep using that model. One thing to know: a reply with tools can take several steps behind the scenes, so it can use the allowance faster than an ordinary message.

How chatting works →

Plans & pricing →

Personas & guidelines →

Tools: sandbox, web, and the Lyra assistant →