Hiya!
I'm going to back up [MENTION=7006]DEFCON 1[/MENTION] with the whole "talk to your DM". I'm a DM and I vastly prefer my players to come to me and say "Here's my idea for a character... he's an elven religious-warrior-monk. They take an oath like that of a druid (to not use metal items, to forsake 'technology', to be in harmony with nature, etc), but are trained in the ways of battle and tactics as a group more than individual-perfection. I think...[etc etc]". Then I can work with the player to craft some custom made archtype for Monk or Fighter or even Cleric that fits into my campaign settings feel and background.
I hate it when I've been DM'ing a particular player who has been playing a straight-laced military man fighter (with soldier background and everything), and then all of a sudden the player says "Oh, I took a level of Rogue last level-up. I'm a stealthy 'shadow ops' kinda guy now". *fume* I'm pretty sure that if the PC's were fighting a big bad wizard guy, then a couple months later I just blurt out "Oh, he isn't a wizard now. He took some other class levels and I added in some dragonblood so he has some dragon stuff now too...he's mostly an assassin half-dragon now.", they'd be... shall we say, "Non-plussed". Additionally it would completely break the immersion and basically throws away all the previous shared story we all built by playing the game in the first place.
Hmmm... I suppose that's why MC'ing is OPTIONAL (much like Feats are). And also why I don't use MC'ing (and soon, no Feats either... more trouble than their worth, IMHO).
^_^
Paul L. Ming