RP-Bench: Roleplay Quality Benchmark

Multi-judge, community-calibrated benchmark for LLM roleplay quality. 2,013 community arena votes / 338 voters / 20 models / 336 multi-turn sessions / 270 flaw hunter scores.

Three core findings drive everything else:

  1. LLM judges disagree with humans. Spearman correlation between Bayesian community ELO and every LLM-judge method is between −0.31 and −0.07. The community measures something the judges cannot.
  2. Engagement and reliability are orthogonal axes. Community ranks Gemma 4 26B / Mistral / Gemini at the top. Frontier closed models (Opus, Sonnet, GPT-4.1) lead on rule-following but trail on community engagement. Pick by use case.
  3. Position bias breaks single-pass pairwise. When we ran the same 168 LLM-judged pairwise comparisons twice with A/B swapped, 64% of pairs flipped their answer. Bidirectional evaluation is mandatory.

Data: lazyweasel/roleplay-bench. Code: github.com/LeviTheWeasel/rp-benchmark. Live community arena: arena.l3vi4th4n.ai.

Bayesian Bradley-Terry ELO from 1,857 clean (suspect-filtered) human pairwise votes. 95% CI is wide (~260 points) — the top tier is statistically tied. Frequentist columns from the 100-shuffle ELO for comparison.


Methodology limitations documented in the experiment design doc. The benchmark is calibrated against ~12 chats by ~5 RP users plus 338 community arena voters. Findings reflect the taste distribution of those participants, not "universal RP quality." For decisions, see the pick-a-model decision tree.