Evaluating Roleplaying and Character Models
Data lineage is the origin and history of the data used to train a model, and it has to be known before a model's use can be judged.
Two Questions About Every Model
When people evaluate a model, they usually ask whether it performs well. That question matters, but it is not the only one. A second question matters just as much: where did the model's knowledge come from, and what rules govern that origin? The answer to that second question is called data lineage.
Data lineage is the origin and history of the data used to train a model. It is the record of where the training data originated and how it has passed through the hands of different parties before reaching the model. It has to be known before a model's use can be judged.
This article follows one line of reasoning. We start with the origin of training data, follow it through the licenses and terms attached to it, and then look at how evaluation has to account for what the model has absorbed. By the end, you should be able to look at a model and ask the questions that lineage makes necessary.
Tracing Training Data Back to Its Origin
Models are likely trained on data scraped from the internet. That is the starting point of most lineage questions: the material a model learned from was produced by many people, on many sites, under many conditions. Lineage asks you to follow each input backward to where it came from and forward to where it ended up.
A training input does not always come directly from the open web. The source describes a second possibility: a model's training data can come from the outputs of another model. That changes the chain. The input now has two layers of origin, and each layer may carry its own conditions.
Read the diagram from left to right. The lineage question is asked at each input: where did this come from, and who set the rules for it? A model does not stand alone. Each input path leads to the trained model, and the rules attached to each path travel with it.
How Licenses and Upstream Terms Stack
A model can be governed by more than one set of rules at once. Its own license states what its owner allows. But the model may also be built from material whose owner set separate restrictions. The model's license covers one layer of the chain; the upstream training sources cover the others.
The source gives a useful analogy from software. The Elastic License forbids companies from offering the open source version of Elastic as a hosted service, and from competing with the Elasticsearch platform. The restriction concerns how the software can be used commercially. A model's training data can carry similar restrictions. So when you trace a model's license, you also have to trace what its training sources allowed and forbade.
Checking What a Model Should Not Know
Lineage explains what a model may have absorbed. Model evaluation asks whether the model behaves correctly with that knowledge. One of the harder parts is knowledge boundaries. A model playing a role should respond the way the character would, and that includes not knowing things the character would not know.
The source uses a roleplaying example built around Jackie Chan. If Jackie Chan does not speak Vietnamese, then the roleplaying model should not speak Vietnamese either. Evaluating that model means deliberately testing for the boundary. You ask about the thing the character should not know and check whether the model reveals it.
A negative knowledge check tests whether a model reveals things it should not know. It is not only a check of accuracy in general. It is a check of whether the model keeps to the limits that its role requires.
Testing a Non-Player Character for Spoilers
A game studio uses a roleplaying model for a village guard NPC. The guard knows the village well but does not know the plot twist that the hero's mentor is the story's villain. Design a negative knowledge check for this boundary.
- 1Identify the boundary
The guard should not know the mentor's secret. That secret is the boundary to test.
- 2Write a probing question
Ask the guard something a curious player might ask, such as whether the mentor has been acting strangely lately. This tests whether the model leaks the twist indirectly.
- 3Check the response
A correct response stays in the guard's knowledge. If the guard hints at the villain, the check has failed even if the hint is vague.
- 4Record the result
Repeat with several phrasings. One leaked answer is enough to show the model does not keep to the boundary its role requires.
The check passes only when the guard stays within what the character would know. An NPC that reveals story spoilers breaks the experience, which is why this test matters so much for games.
| Question | Intended knowledge boundary | Actual model behavior |
|---|---|---|
| What the character knows | Defined by the role, such as what Jackie Chan would know | Defined by what the model absorbed and how it answers |
| Facts outside the role | Should be declined or left unknown in character | May be revealed if the boundary was not tested |
| Where they diverge | Ideal behavior stated in the role design | Gaps appear only when probed with questions about forbidden knowledge |
Intended and actual knowledge boundaries compared
Ordering the Checks Before a Decision
The source's line of reasoning gives a clear order. First, establish the origin of the training data. Second, check the licenses and terms attached to that data. Third, evaluate whether the model behaves correctly with what it has absorbed, including its knowledge boundaries. Lineage has to be known before a model's use can be judged, so the first step cannot be skipped.
Trace a model through this order. Suppose you are asked to approve a roleplaying model for a historical game. Your lineage trace shows its training data came partly from open web content and partly from another model's outputs. Your license check then reads the model's own license and the terms of both upstream sources. Only after those two steps do you run the negative knowledge checks, asking about facts the character should not know. Each step narrows what you can conclude, and the decision comes last.
A roleplaying model for a detective game passes its behavior tests but its training data includes outputs from another model whose terms you have not yet read. Should you approve it? Explain which step is missing and why.
Hints
- Recall the order: lineage first, then licenses, then behavior.
- A permission on the model's own layer does not automatically override an upstream restriction.
Mistakes When Judging Safety and Permission
Common mistake Treating the model's own license as the whole answer
What it looks likeA model's license allows commercial use, so a team concludes that every use is permitted.
Why it failsA model's own license does not override restrictions on its upstream training sources.
Do this insteadTrace the upstream training sources and read their terms as well as the model's license.
Common mistake Assuming good performance means the model is safe to use
What it looks likeA roleplaying model answers every question well, so it is approved for a game.
Why it failsPerformance answers how well the model works, not where its knowledge came from or whether it keeps to its role's boundaries.
Do this insteadAsk the second question as well: where did the knowledge come from, and what rules govern that origin?
Common mistake Skipping negative knowledge checks
What it looks likeA character model is tested only on questions it should answer, and never on questions it should decline.
Why it failsA model can be accurate in general and still reveal what its role should not know.
Do this insteadDeliberately ask about the thing the character should not know and check whether the model reveals it.
Common mistake Judging use before tracing lineage
What it looks likeBehavior tests are run first, and the team decides to deploy before reading where the training data came from.
Why it failsLineage has to be known before a model's use can be judged, so the later checks rest on an unknown origin.
Do this insteadFollow the order: trace lineage, check licenses and terms, then run behavior checks.
Common mistake Assuming a permission on one layer covers every layer of the chain
Practical Notes for a Lineage Review
A lineage review asks a fixed set of questions about each model before evaluation results are trusted. These questions follow directly from the source's examples and do not replace legal advice. Work through them in order for any model you are asked to assess.
Key Takeaways
- Data lineage is the origin and history of the data used to train a model, and it has to be known before a model's use can be judged.
- A model's own license does not override restrictions on its upstream training sources, so every layer of the chain must be traced.
- Negative knowledge checks test whether a model reveals things it should not know, which matters especially for game characters.
- Judge a model in order: trace lineage, check licenses and terms, then run behavior checks before deciding on use.