Nalia

Nalia is a Chaotic Good Thief/Mage (dual-class) who can be recruited in BG2.

Whilst Nalia makes a poor thief, she is a useful mage who can be picked up early in the game. Unless your main character is also a mage, you may want to keep her around until Imoen rejoins the party.

Baldur's Gate 2

Nalia can be recruited at the Copper Coronet from chapter 2 onwards. She will approach the party automatically when you enter her field of vision, there is no need to explicitly engage her in conversation.

Nalia has a tough but achievable side quest as part of her recruitment process, although you can delay the quest by offering to meet her at her home (there is no time limit imposed on recruiting her if you do this). You can also agree to take up the quest without recruiting Nalia, and you will receive the same rewards either way. At the end of the quest, Nalia will ask if she can remain in your party indefinitely.

Whilst Nalia can be a bit annoying with her insistence on helping those 'less fortunate' - regardless of whether they want such assistance - she generally gets on with good and neutral party members, although she may exchange words with more mature characters who view her as somewhat naive.