Charlie's just fine
I originally started writing this as a response to used_songs's comment, but it got a little long.
I don't think that Charlie Eppes has Autism or Asperger's or any other kind of social or developmental disability because he hasn't been portrayed that way. Realistically speaking, I think it's very much a possibility, but that's not the way that DK has presented the role. Charlie has passion but lacks eccentricities. Now, I could see Larry has having Asperger's. There's a certain something in the way that Peter MacNicol has interpreted and presented the character with these mannerisms that make red flag go off in my head.
If you watch A Beautiful Mind, Russell Crowe is implementing schizophrenic ticks right off the bat from the first scene (well, it's actually the second scene, out at the punch bowl where he meets the other mathematicians). Dustin Hoffman brilliantly portrays autistic response to stimuli in Rain Man (and Alan refers to Larry as "Rain Man" in the S2 episode "All's Fair"). Christian Clemenson does a great (though arguably grandiose) performance as an attorney with Asperger's on Boston Legal. These are very clear examples of characters with mental/social/developmental disorders, and they're not things that we've seen from Charlie.
Charlie actually seems rather well-adjusted as we get to episodes in season three (and even some in season two). In season three, we've got a character that is very comfortable with being a part of a high-intensity team, adjusted to defending his work to those outside the math community, and pretty damn charismatic (though that could just be my crush talking). His ambivalence towards interacting with college sponsors that we see with Millie has more to do with personal preference than any sort of disorder because we don't have those ticks or behaviors to prove otherwise.
Is it possible to have a genius who isn't fucked up in some way? I think so. Granted, I feel the brain sacrifices some skills in favor of others, so it might make sense that the more intelligent a person is, the more he falters in other areas, and extreme genius could therefore imply extreme "retardation" in other areas to the extent that it would manifest in the form of a disorder, but we have little in canon to suggest that.
Frankly, and I say this with all due respect, the show really does have a character roster of Marty Stus. They do have some bleak aspects in their background (namely Megan's teenage rebellion and the revelation about Colby in "The Janus List," which will undoubtedly be turned into something else in season four as Dylan Bruno remains a cast member throughout the duration of S4), but the characters are now at a point where they're very skilled, dependable, funny, dedicated, and lovable for all the right reasons. Even Don's therapy sessions didn't give big revelations; he's a leader with control issues - that's to be expected as far as I'm concerned. So would TPTB pull Krumholtz aside and say, "Hey, we want to expose Charlie has having X disorder"? I highly doubt it. Existence of a disorder doesn't necessarily make a character less enjoyable (the previously mentioned Boston Legal Asperger's character Jerry Espenson has now been made a full cast member), but it does make him less perfect, and I don't believe that's an intention of TPTB.
I think we can safely assume that Charlie doesn't have any of the aforementioned disorders, though don't let that deter you from writing to the contrary. After all, many of us write Don/Charlie, and that's about as improbable as it gets.
I don't think that Charlie Eppes has Autism or Asperger's or any other kind of social or developmental disability because he hasn't been portrayed that way. Realistically speaking, I think it's very much a possibility, but that's not the way that DK has presented the role. Charlie has passion but lacks eccentricities. Now, I could see Larry has having Asperger's. There's a certain something in the way that Peter MacNicol has interpreted and presented the character with these mannerisms that make red flag go off in my head.
If you watch A Beautiful Mind, Russell Crowe is implementing schizophrenic ticks right off the bat from the first scene (well, it's actually the second scene, out at the punch bowl where he meets the other mathematicians). Dustin Hoffman brilliantly portrays autistic response to stimuli in Rain Man (and Alan refers to Larry as "Rain Man" in the S2 episode "All's Fair"). Christian Clemenson does a great (though arguably grandiose) performance as an attorney with Asperger's on Boston Legal. These are very clear examples of characters with mental/social/developmental disorders, and they're not things that we've seen from Charlie.
Charlie actually seems rather well-adjusted as we get to episodes in season three (and even some in season two). In season three, we've got a character that is very comfortable with being a part of a high-intensity team, adjusted to defending his work to those outside the math community, and pretty damn charismatic (though that could just be my crush talking). His ambivalence towards interacting with college sponsors that we see with Millie has more to do with personal preference than any sort of disorder because we don't have those ticks or behaviors to prove otherwise.
Is it possible to have a genius who isn't fucked up in some way? I think so. Granted, I feel the brain sacrifices some skills in favor of others, so it might make sense that the more intelligent a person is, the more he falters in other areas, and extreme genius could therefore imply extreme "retardation" in other areas to the extent that it would manifest in the form of a disorder, but we have little in canon to suggest that.
Frankly, and I say this with all due respect, the show really does have a character roster of Marty Stus. They do have some bleak aspects in their background (namely Megan's teenage rebellion and the revelation about Colby in "The Janus List," which will undoubtedly be turned into something else in season four as Dylan Bruno remains a cast member throughout the duration of S4), but the characters are now at a point where they're very skilled, dependable, funny, dedicated, and lovable for all the right reasons. Even Don's therapy sessions didn't give big revelations; he's a leader with control issues - that's to be expected as far as I'm concerned. So would TPTB pull Krumholtz aside and say, "Hey, we want to expose Charlie has having X disorder"? I highly doubt it. Existence of a disorder doesn't necessarily make a character less enjoyable (the previously mentioned Boston Legal Asperger's character Jerry Espenson has now been made a full cast member), but it does make him less perfect, and I don't believe that's an intention of TPTB.
I think we can safely assume that Charlie doesn't have any of the aforementioned disorders, though don't let that deter you from writing to the contrary. After all, many of us write Don/Charlie, and that's about as improbable as it gets.