You have to talk to Berun Ghastkill with them in the party or they will leave. Consider it their 'quest'. They don't actually play any role in the mines itself.
The developers put that in more to point you in the right direction rather than to serve a purpose in the actual quest. Given how open ended the game is it can be somewhat difficult to figure out what you are "supposed" to do.
I'm assuming this should have been in the "no spoilers" section? The OP seems to be playing the game for the first time.
@Meowzor: You can potentially find better party members, but the ones you've mentioned are fine. You can't, for example, get party members of significantly higher level than the rest of your party. What makes you want to find new companions? Perhaps we can help you get more value out of the ones you've already got.
oh ok i already talked to ghastkill i guess I can dump them and get some better party members
Actually, you can't get any better party members than Monty and Xzar.
It obviously depends on your charname and the alignment you're going for. If you indeed play for the first time, a spoiler-free advise would be: keep the pair of your own alignment. If you are good, dismiss the evil ones. If you are evil, dismiss the good ones. Neutral gets along with either alignment (except in this case, Jaheira can be counted as good, since she is paired with Khalid. You can seperate pairs though by locking the one you don't want in a house, close the door and then dismiss them. Just never open the door again, this way the half you want to keep will stay.)
Edwin is a better mage than Xzar, but he is not a better NPC. Edwin does have superior spellpower and his forbidden school is arguably less of a loss than Xzar's, but Xzar has better stats.
Edwin's redeeming quality is high con, but then, you have frontline beasts like Shar-Teel with less con than Xzar. Xzar makes up for it with high dex and very decent strength for a mage. Edwin starts with Quarterstaff prof. Unless you are using the ranged wizard staff mod, this is a total waste, while Xzar starts with Dagger and is surprisingly reliable with Throwing Daggers. Not to mention that Xzar, as only NPC, can dual to 2 different classes - he is 1 tome each away from Thief and Cleric, as which he can surpass all actual clerics in terms of Wisdom and extra spells. So as a mage, I guess we can all agree that Edwin takes the crown, even compared to charnames. But as NPC and highly versatile party member, Xzar rules all. (Sorry, Tiax.)
You people are a bad influence on this innocent new player. Xzar and Montaron are EVIL, and cannot be trusted!
Seriously though, I think it should be mentioned that Jaheira and Khalid are 'canon' NPCs, they are the pair Gorion entrusted to keep Charname safe, and their story is much more significant in BG 2. Also they are pretty solid characters from a gaming perspective too.
Incidentally the other canon NPCs are Minsc, Dynaheir and Imoen.
I don't think it should matter that the NPCs are canon, except that maybe it's wise to learn how to play them a little so that you'll know how to use them
Xzar is just completly useless but still introduce a way of playing mage a while back in bg1 when there were no tutorial. Same as montaron to show that you could dual-class and be a badass. That's mostly their goal. Other than that, kill them when you find new npcs
Edited : Imoen was to show new players that never readed human description that they can dual-class but they need to reach same level to keep on using their ability of the class
Imoen is a great NPC in almost every way, so she is certainly not there just to show off game mechanics. She is a great thief, pretty tough for a nob-fighter and can become a very accomplished mage. Plus she is kinda central to the plot and is generally a nice companion to have.
I mean Edwin/Xzar/Montaron are funny for a while, but if they were real people, you wouldn't really want them as your friends.
I know what you mean for Imoen and I always have her in my party. What I meant is for the beginning, what the use of Imoen to show to new players as a tutorial. Edwin is the only evil character my group ever had cause of his +1 spell slot
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@Meowzor: You can potentially find better party members, but the ones you've mentioned are fine. You can't, for example, get party members of significantly higher level than the rest of your party. What makes you want to find new companions? Perhaps we can help you get more value out of the ones you've already got.
Edwin is a better mage than Xzar, but he is not a better NPC. Edwin does have superior spellpower and his forbidden school is arguably less of a loss than Xzar's, but Xzar has better stats.
Edwin's redeeming quality is high con, but then, you have frontline beasts like Shar-Teel with less con than Xzar. Xzar makes up for it with high dex and very decent strength for a mage. Edwin starts with Quarterstaff prof. Unless you are using the ranged wizard staff mod, this is a total waste, while Xzar starts with Dagger and is surprisingly reliable with Throwing Daggers. Not to mention that Xzar, as only NPC, can dual to 2 different classes - he is 1 tome each away from Thief and Cleric, as which he can surpass all actual clerics in terms of Wisdom and extra spells. So as a mage, I guess we can all agree that Edwin takes the crown, even compared to charnames. But as NPC and highly versatile party member, Xzar rules all. (Sorry, Tiax.)
Anyways, who does not like travelling around with a Wise and intelligent person whose mind has snapped, and a murderous halfling?
Seriously though, I think it should be mentioned that Jaheira and Khalid are 'canon' NPCs, they are the pair Gorion entrusted to keep Charname safe, and their story is much more significant in BG 2. Also they are pretty solid characters from a gaming perspective too.
Incidentally the other canon NPCs are Minsc, Dynaheir and Imoen.
Edited : Imoen was to show new players that never readed human description that they can dual-class but they need to reach same level to keep on using their ability of the class
Imoen is a great NPC in almost every way, so she is certainly not there just to show off game mechanics. She is a great thief, pretty tough for a nob-fighter and can become a very accomplished mage. Plus she is kinda central to the plot and is generally a nice companion to have.
I mean Edwin/Xzar/Montaron are funny for a while, but if they were real people, you wouldn't really want them as your friends.
I know what you mean for Imoen and I always have her in my party. What I meant is for the beginning, what the use of Imoen to show to new players as a tutorial. Edwin is the only evil character my group ever had cause of his +1 spell slot