Neera

Neera is a Chaotic Neutral Wild Mage who can be recruited in all three games. She's a powerful spellcaster, but the random effects of her magic may be too much for some players.

In all games Neera will come into conflict with Edwin Odesseiron, and you cannot keep both characters in your party simultaneously for long.

Baldur's Gate 1

Neera can be found in Beregost early in the game. If you recruit her, after a while she will open up a side quest.

Siege of Dragonspear

Neera is recruitable part way through the game.

Baldur's Gate 2

You will meet Neera early in the game if you visit the Bridge District. However, she will teleport away before you have chance to speak to her. She will appear again when you move between locations and ask you to meet her at a location which she will mark on your map. You can only recruit her if you go to this location and accept her side quest.

Romance

If your character is male, he can enter into a romance with Neera. Romance options are available in all three games and are largely independent - you can romance Neera in BG2 even if she wasn't in your party in BG1.

Without giving too much away, the guide to successfully romancing Neera is to flirt outrageously with her and generally act confident, as she will draw strength from this. Oh, and don't say anything bad about wild mages! Do not expect much romance in BG1 though, you can easily exhaust all the dialogue options by the end of chapter 2.