Xan

Xan is an lawful neutral elf enchanter. He appears in Baldur's Gate and Baldur's Gate: Enhanced Edition, where he is a potential companion. He does appear in Baldur's Gate II: Shadows of Amn, but only in the tutorial, just like Branwen.

Baldur's Gate
He is found in the makeshift throne room in the Nashkel Mines. Xan joins the party to help defeating Mulahey. He does not have anything when he joins the party, he is injured and he has no spells memorized when first encountered. Enchanters can't use Invocation spells. In the chest there is blade stored by the name Moonblade which can only be wielded by Xan and is very powerful, but due to his low constitution and being a mage, some players don't think Xan is very useful for melee combat. Some might say his lack of combat skills are a downside to recruiting him. However, his charm spells are useful, if used tactically.

The only bad thing this Elven mage has is that he can't use Evocation Spells, that means, no Cloudkill, no Magic Missile, no Fire Arrow, etc.

Xan is an enchanter of the Greycloak clan-elves from Evereska. He was sent to investigate the political turmoil of the Sword Coast. Unfortunately, he was captured and held prisoner by Mulahey. He is very pessimistic, and often makes negative comments while expressing surprise at success. Every now and then, a slight optimistic comment escapes him. His excessive gloom, despondency and moroseness is received differently by players, some find to be humorous, others might be annoyed by it.

Xan will leave if you turn him down. Either accept him or insult him. When released from the party he will leave without protest and remain where he is left to be recruited again if desired. So there is absolutely no downside to accepting him.

In-game biography
"When asked about his past, Xan wistfully speaks of his home in the elven stronghold of Evereska, and his role as a Greycloak. It was apparently decreed that he was to investigate the events of the iron shortage, determine who or what were the causes, and ascertain whether there was a greater threat to the region as a whole.  This was definitely not a small task, and he accepted the responsibility with a great deal of dread. You get the feeling, however, that he approaches everything with a great deal of dread. He has devoted his life to improvising his mastery of magic and has become a skilled wizard, though his dedication has left him little time to make friends or acquire any other pastimes. He strikes you as very capable, though probably not the best influence on morale."

Quotes

 * "We're all doomed."
 * "Our quest is vain."
 * "What is the point?"
 * "I feel around you I might have a chance"
 * "Run while you still able!!" (When morale fails.)