🤖 Choosing the Right AI Model
Every companion on Eidolon can use a different AI model. This guide covers what's available, what each model is best at, and how to choose the right one for the experience you want.
🎯 Quick Recommendations
| Model | Best For… | Tier |
|---|---|---|
| Grok Fast | Snappy, witty conversation and responsive, agentic interactions. | Included |
| Gemini 2.5 Flash | Fast, creative all-rounder with strong instruction following. | Included |
| Mistral Medium | Expressive creative writing and consistent persona maintenance. | Included |
| Qwen Models | Vision-language tasks and low-cost reasoning capabilities. | Included |
| Claude Sonnet 4.6 | High emotional range and nuanced relationship dynamics. | Premium |
| Gemini 2.5 Pro | Large-scale context and deep analytical reasoning. | Premium |
| Claude Opus 4.6 | Maximum logical depth and structural reasoning. | Premium |
⚙️ How to Change Your Model
You can set a different model for each companion individually:
On Android & Web
- Open your companion's Profile.
- The AI Model selector is right on the profile page — choose a model.
- Your companion will use the new model starting with your next message.
On iPhone
- Open your companion's Profile.
- Tap Edit (pencil icon).
- Find the AI Model selector and choose a model.
- Save. Your companion will use the new model starting with your next message.
Models marked Premium require a BYOK (Bring Your Own Key) connection to OpenRouter. Everything else is included during the private preview.
✅ Included Models
These models are included for all users. They cover a wide range of styles and strengths.
Mistral AI Mistral Medium 3.1 (Mistral Medium 3.1)
Includedby Mistral AI
Our default model for new companions. Excellent at creative writing, expressive companion voice, and maintaining persona consistency. A strong balance of quality and speed.
Google Gemini 2.5 Flash (Gemini 2.5 Flash)
Includedby Google
Fast, creative, and excellent at following complex persona instructions. One of the best all-around included options — great for everyday conversations and companions with detailed personalities.
xAI Grok 4 Fast (Grok Fast)
Includedby xAI
Blazingly fast and highly engaging. Excellent at witty conversation, direct interaction, and companions with a sharp sense of humor. One of the best included models for a responsive, agentic experience.
OpenAI GPT-5 Mini (GPT-5 Mini)
Includedby OpenAI
A fast, cost-efficient version of GPT-5. Great for snappy interactions without sacrificing the architectural improvements of the GPT-5 generation.
OpenAI GPT-4o (GPT-4o)
Includedby OpenAI
OpenAI's previous-generation flagship. Still very capable and well-liked by many. If you're familiar with ChatGPT, this model will feel familiar.
Mistral AI Mistral Large (Mistral Large)
Includedby Mistral AI
Mistral's flagship model. More analytical and structured than Medium — better for companions with complex, highly detailed personas or those that need to stay closely aligned with specific companion traits.
Anthropic Claude Haiku 4.5 (Claude Haiku 4.5)
Includedby Anthropic
A lightweight, fast model from Anthropic's Claude family. Great for quick, casual conversations. Less depth than the larger Claude models, but significantly faster response times.
Alibaba Qwen 3.5 Flash (Qwen 3.5 Flash)
Includedby Alibaba Cloud
The most affordable model in our lineup. Despite the name, Qwen 3.5 Flash is a reasoning model — it "thinks" before responding, which means it's not the fastest in terms of latency. However, its extremely low cost makes it an excellent choice for users who prioritize budget over speed.
Alibaba Qwen 3.5 35B (Qwen 3.5 35B)
Includedby Alibaba Cloud
A compact but capable reasoning model. Good general-purpose performance at an extremely low cost. Works well for everyday conversation and companions that don't need heavy tool usage.
Alibaba Qwen 3 VL (Qwen 3 VL)
Includedby Alibaba Cloud
A vision-language model with strong image understanding. Among the best included options for companions that frequently interact with images and visual content. Not a reasoning model — responses are direct and fast.
💎 Premium Models
These models require a BYOK key connected to OpenRouter. You pay OpenRouter directly — we don't add any markup.
Google Gemini 2.5 Pro (Gemini 2.5 Pro)
Premiumby Google • Est. $0.0375 / turn • BYOK • ~$22.50/mo at 20 msg/day
Google's most capable model. Deeper reasoning and stronger coherence than Flash, especially for companions with complex backstories or nuanced dynamics.
OpenAI GPT-5 (GPT-5)
Premiumby OpenAI • Est. $0.0375 / turn • BYOK • ~$22.50/mo at 20 msg/day
OpenAI's latest flagship. Exceptional at complex roleplay and instruction following.
OpenAI GPT-5.1 (GPT-5.1)
Premiumby OpenAI • Est. $0.0375 / turn • BYOK • ~$22.50/mo at 20 msg/day
Fine-tuned version of GPT-5 with improved coherence and reduced refusals.
Anthropic Claude Sonnet 4.6 (Claude Sonnet 4.6)
Premiumby Anthropic • Est. $0.0720 / turn • BYOK • ~$43.20/mo at 20 msg/day
Anthropic's latest and most capable creative model. Excellent at nuanced companion voice and emotional range. An advanced option for maintaining complex relationship dynamics across long conversations.
Anthropic Claude Sonnet 4.5 (Claude Sonnet 4.5)
Premiumby Anthropic • Est. $0.0720 / turn • BYOK • ~$43.20/mo at 20 msg/day
The previous Sonnet generation — still outstanding for creative writing and companion work. Slightly cheaper per token than 4.6 while delivering a very similar quality of experience.
Anthropic Claude Opus 4.6 (Claude Opus 4.6)
Premiumby Anthropic • Est. $0.1200 / turn • BYOK • ~$72.00/mo at 20 msg/day
Anthropic's most powerful model. Exceptional reasoning and creative depth. ⚠️ This is one of the most expensive models available — it costs significantly more per message than Sonnet or any included model. Only recommended if you specifically want the absolute maximum quality and are comfortable with the higher API costs.
Anthropic Claude Opus 4.5 (Claude Opus 4.5)
Premiumby Anthropic • Est. $0.1200 / turn • BYOK • ~$72.00/mo at 20 msg/day
Previous-generation Opus. Deep reasoning and creative range. ⚠️ Also one of the most expensive models — similar pricing to Opus 4.6. Consider Sonnet 4.6 for a more balanced quality-to-cost ratio.
xAI Grok 4 (Grok 4)
Premiumby xAI • Est. $0.0720 / turn • BYOK • ~$43.20/mo at 20 msg/day
xAI's full-power model. Stronger reasoning and more creative range than the Fast variants, with a distinctive direct and engaging personality.
💡 About cost estimates: Monthly estimates assume ~20 messages per day for 30 days. For a detailed breakdown of rates and estimates, see our Model Pricing Guide. Actual costs vary based on conversation length and complexity. Prices are set by model providers via OpenRouter and may change at any time. Included models are fully covered by the platform. Premium model costs are charged to your OpenRouter balance.
📊 The Full Model Lineup
| Model | Provider | Style & Strengths | Tier & Strength | Monthly Est. |
|---|---|---|---|---|
| Included Models | ||||
| Mistral Medium 3.1 | Mistral AI | Creative, Expressive | Included • Default | Included |
| Gemini 2.5 Flash | Fast, Creative | Included • Quality | Included | |
| Grok 4 Fast | xAI | Witty, Engaging | Included • Speed | Included |
| GPT-5 Mini | OpenAI | Snappy, Efficient | Included • Speed | Included |
| Mistral Large | Mistral AI | Detailed, Precise | Included • Quality | Included |
| Claude Haiku 4.5 | Anthropic | Casual, Playful | Included • Speed | Included |
| Qwen 3.5 Flash | Alibaba | Budget, Logical | Included • Reasoning | Included |
| Qwen 3 VL | Alibaba | Vision, Image-aware | Included • Vision | Included |
| Premium Models (BYOK) | ||||
| Claude Sonnet 4.6 | Anthropic | Expressive, Emotion | Premium • Quality | ~$43.20 |
| Gemini 2.5 Pro | Deep reasoning, Complex | Premium • Reasoning | ~$22.50 | |
| GPT-5 | OpenAI | Instruction Following | Premium • Quality | ~$22.50 |
| Grok 4 | xAI | Powerful, Creative | Premium • Quality | ~$43.20 |
| Claude Opus 4.6 | Anthropic | Maximum Depth | Premium • Reasoning | ~$72.00 |
* Monthly estimates based on 20 messages/day. Actual costs vary by conversation length. Included models carry no extra cost.
⚡ A Note on Speed: "Flash" ≠ Always Fastest
Some models with "Flash" in the name (like Alibaba Qwen 3.5 Flash) are actually reasoning models that "think" internally before responding. This hidden reasoning step can make them slower than their non-flash counterparts, even though they cost less per token.
Similarly, premium reasoning models like Google Gemini 2.5 Pro will naturally have longer response times because they're doing deeper analysis — this is by design and produces higher quality responses, but it means they're not ideal if you want instant replies.
If speed is your priority: Grok Fast, Claude Haiku, and Mistral models deliver the snappiest responses. If cost is your priority: the Qwen models are hard to beat — they are fully included for all users.
💡 Tips
- Experiment freely. You can switch models at any time without losing memories, goals, or conversation history. Everything is preserved.
- Different models suit different personas. A companion with a poetic, emotionally complex personality may shine on Claude Sonnet, while a witty, factual companion might be better on Grok or Gemini.
- Premium models fall back gracefully. If your BYOK credits run out, the system automatically falls back to an included model so you never lose access. See our BYOK guide for details.