Ambi/Remo/Anniyan - Probably the most famous example in this corner of the world. Ambi (pronounced 'humpy' with a silent h) is a fundamentally sad person who has 2 major goals in his life and spawns 2 alternative identities to achieve said goals, the lover a.k.a Remo (pronounced 'Ray-Moo' generally with a soft moan) and the hair model "The ANNIYAN" ( pronounced "aargh!!" ). As a side story "The ANNIYAN" also wants to punish negligence, lack of compassion (etc) and therefore embarks on a killing spree. In the end the truth is discovered and he is sent to a secret facility *cough* Arkham *cough* for treatment.
Contrary to popular belief this was not simply a technique used to conveniently separate the 3 main aspects a standard Tamil film (humour, romance and violence) and illustrate how they join together as one package in the end like a film making workshop.This was in fact a genuinely serious film as clearly demonstrated by Yana Gupta's meaningful cameo. The important fact to note is that he was treated with compassion and sent for experimentation treatment.
Pregnancy - The oldest known example. Fully licensed to go cuckoo whenever and wherever they may please. Out of respect for my mother I will not make any jokes here. They are treated with reverence, extreme respect and no small amount of caution.
At this juncture I must point out that MPD seems to be spreading quite rapidly, since some of my friends too, seem to have suddenly spawned alternative identities, with a desire to save the environment as is evident here and here. To me however, the phrase going green will always mean one and only one thing.
Which in turn brings me to my third example "THE HULK". As with all changes in nature, the presence of a driving force is necessary to induce MPD. The hulk is splendid example in the category of "Artificially induced multiple personality disorder" or AIMPD in short (ie) the inducing of cuckooness through the effect of any external chemical agents on the body. Note: pregnancy does not come under this category.
In THE HULK's case it is gamma rays. As a result of experiments which he performed on himself, Bruce Banner, whenever he gets angry transforms into the person we have all come to know and love.
Please note that he is not however "your friendly neighbourhood HULK" and if you tick him off, he will eat you. The HULK is being unfairly hunted by governments (racism's latest avatar) and as a consequence has gone into hiding. Those who knew him well describe him to be a deeply religious and pious human being.
Dr. Jekyll and Mr. Hyde - An example from classical literature. The severity of the condition necessitated special drugs to bring him back to his normal state. Nobody knows what actually happened to him. This lack of evidence leads me to believe that this story may be fictitious.
For today's internet savvy generation, perhaps the most prominent yet unnoticed example
This is rumored to be the plot origin for Anniyan.
This wide disparity in public reaction to these cases has forced me to keep my secret under wraps. Hence, I have decided that my alter ego will remain hidden until such time as the world needs her.
PS: No offence meant to anybody
Note: Smileys courtesy eternal thinker