The Enclave created my people as a slave warrior race. They enhanced our intellect hoping we could better understand their commands, and yet not recognize our status as slaves. They failed; we are much more intelligent than they suspect.
One of the most successful results of the Enclave's bioweapons program, Xarn, like the rest of his pack, managed to successfully hide his intelligence from his masters. Trouble is, he trusted the wrong person: Dr. Schreber used him to verify his thesis that the deathclaws are a danger to the Enclave and formulate a report recommending their extermination.
If released, he heads east into the wastes toward Vault 13, never to be heard from again.
Since Xarn joins the player's party temporarily, he becomes a powerful melee ally. He has high hit points and innate resistance, but requires steady healing with stimpaks to keep him alive. He will leave when the player opens the exit into the air vent in the ward.
↑Fallout Bible 6: "e. Xarn the Intelligent Deathclaw from Navarro According to F2 designer John Deiley, Xarn was supposed to go back to Vault 13 and warn the Vault about Horrigan's attack, but he never made it (in the original design, he was supposed to be able to go back and save all the deathclaws and warn them about the Enclave, but this didn't make it in). He was last seen wandering east into the wastes toward Vault 13 - he never made it, however, so his final destination is unknown."