Dairon

 is an elf monk working for the Archive of the Cobalt Soul, a library in Zadash. Her monk archetype is the Way of the Cobalt Soul, published in Critical Role: Tal'Dorei Campaign Setting. As an NPC, Dairon is played by Matthew Mercer.

Appearance
When Dairon first appeared, she was hooded and wearing baggy grey pants. All Beauregard could see of her was a thin, muscular figure, neither particularly masculine nor feminine, and dark skin. Dairon later lowered her hood to reveal elvish features and a bald head.

After Archivist Xenoth's failure to find Beauregard and return her to the Archive of the Cobalt Soul in Zadash, Expositor Dairon pursued and found the wayward monk in Trostenwald. After earning Beauregard's respect by easily outclassing her in unarmed combat, Dairon taught Beauregard to use the third-level "Extract Aspects" ability from the Way of the Cobalt Soul archetype for the monk class.

Beauregard trained with Dairon at the Cobalt Soul in Zadash.

Jester Lavorre, at Beauregard's behest, cast Sending to find out Dairon's status. Dairon claimed she was recovering from injuries in Bladegarden.

Dairon saw the Mighty Nein enter the Four Corners tavern while she was disguised as a drow. She stared at Beau, but rebuffed Beau and Fjord's attempts to talk to her. When Beau entered the fighting pit with Jester, Dairon entered as well. After Jester and the ogre went down, Dairon narrowly won over Beau. Dairon claimed the money, jade, and diamond from the fight, but indicated to Beau that she wanted to speak. Once Beau, Jester, and Frumpkin followed her into a shack outside of the bar, Dairon dropped her disguise and gave Jester back the diamond. She revealed that she had lied in an attempt to keep Beau in the Dwendalian Empire and asked if they could share notes.

Beauregard
Dairon sees Beau as an apt pupil and believes her rebellious nature is a boon.

Monk Abilities

 * Deflect Missiles
 * Evasion
 * Extra Attack
 * Ki
 * Flurry of Blows
 * Patient Defense
 * Martial Arts (1d8)
 * Monastic Tradition: Way of the Cobalt Soul
 * Extort Truth
 * Extract Aspects
 * Ki-Empowered Strikes
 * Mind of Mercury
 * Preternatural Counter
 * Purity of Body
 * Slow Fall
 * Stillness of Mind
 * Stunning Strike
 * Tongue of the Sun and Moon
 * Unarmored Defense
 * Unarmored Movement

Quotations

 * "We wade in the filth of society, we weed out the corrupt, we pursue the secrets and evils of the world and expose them to the light, we twist the arm of the unjust until they spill their mysteries, we are the spies, we are the hunters, we are the watchmen to those who rule, we are not kind, we are forthright, we are truth."
 * "Do what you must. Travel the world. Use what I've taught you, learn about injustice. Those you don’t trust, follow them, bend them. Make them tell the truth and admit their guilt. Find wherever corruption is, root it out and let the system do its job. And if the system isn’t doing its job, destroy the system." (parting instructions to Beauregard)

Trivia
dairon uses both she/her and they/them pronouns ( Source )