Montaron and his companion Xzar are Zhentarim sent to the Sword Coast to investigate the causes of the recent Iron Crisis. As the plot evolves, it becomes clear that someone's trying to frame the Zhentarim for the events occurring around the city of Baldur's Gate and Nashkel. Since the Zhentarim are not particularly benevolent and have a fearsome reputation, the duo prefers to work undercover, pretending to be mere adventurers.
As with all evil party members, Ajantis will eventually attack Montaron. However, it's possible to call Ajantis off by giving him another command when he attacks. A fight between the two can also be avoided by having Xan in the party, as he is able to talk Ajantis down.
Montaron is disgusted by Alora's friendliness and kindness, and expresses wonder that she's even managed to survive this long in the thieving profession with an attitude like that. Alora doesn't like Montaron all that much and thinks he is a huge grump.
Montaron dislikes Garrick and sees the bard as a fool who is going to get himself killed one of these days.
Montaron talks of killing party members, and it's not just bluff or bluster. If kept in the party long enough, he will provoke Khalid into a fight, If that happens, Jaheira will join Khalid to fight Montaron and Xzar to death.
Minsc and Montaron strongly dislike each other. Montaron finds Minsc's do-goodery disgusting, and Minsc distrusts Montaron. Boo does not trust Montaron either.
Montaron finds Quayle annoying and pretty much thinks he's an incompetent idiot.
Montaron thinks Skie is incompetent and is surprised she hasn't gotten herself killed yet.
Xzar is Montaron's co-worker and traveling companion. Though the two will always join the party as a pair and refuse to travel separately, there is little love between them. Xzar and Montaron clearly dislike each other, and Montaron implies more than once he's been plotting to put Xzar down. Should Xzar die, Montaron will react happily and claim that it saves him the trouble of killing Xzar himself.
Yeslick and Montaron strongly dislike each other. Montaron cannot stand Yeslick's goody-goody attitude, and Yeslick finds Montaron's eagerness to resort to violence both disturbing and misguided.
As a halfling with 15 constitution, Montaron receives a -4 bonus on saves against Death, Spells and Wands.
In Enhanced Editions, companions who have fewer XP than protagonist at the time of their first joining will be given a certain amount of experience points (XP) for you to manually level them up to gain more control of their status.
When asked about his past, MONTARON openly threatens you with bodily harm. He seems quite dangerous, and more than willing to engage in gratuitous violence. It would appear that he cares little for life, including his own. He works grudgingly with Xzar, even though he obviously despises the man. Whoever their employers are, they must be powerful indeed. These two would likely kill each other without a presence over their heads preventing it. Montaron might be willing to discuss the whole matter with you, but you get the feeling that you probably would not wake up the next morning.
Montaron does not appear in Shadows of Amn, but Xzar wants you to search in the Harper Headquarter in the Athkatla Docks for him during a side-quest. You will soon find out that he has been polymorphed into a bird, which you give to Xzar, but when the bird is transformed in human form, you find out this is a trick, as the bird was not Montaron, but an assassin of the Harpers which kills Xzar. You can find Montaron's body in a chest in Harper Headquarter when visiting the building later.
Montaron is a very psychotic and aggressive character, threatening all his companions with bodily harm. He is also very reserved and secretive, using the usual threats to discourage nosing around.
Despite travelling with Xzar, Montaron despises the Necromancer and will express relief over his eventual demise. He also holds no respect to anyone in his party, looking at potential companions as pack-mules and potential victims rather than peers.