Before we begin to delve deeper into the definition of this character type, I have to say now, this is not the same as ‘Damsel in Distress’. For one thing, they are not necessarily female. There are similar characteristics yet there are enough differences to seperate the two. The most obvious (apart from the aforementioned) is the ‘vulnerable’ does not need rescuing, in the traditional sense.
However, they do have issues which make them potentially vulnerable from outside sources. The traditional vices; money, drugs, drink only partially cover the gamut of issues and yet this character is more than just a two-dimensional stereotype. Other characteristics likely to be found are naivety and gullibility.
Classic vulernable people are the young and elderly. The young, because they have no life experience and are innocent. The elderly, because they are in no position to fight back. Other variants include those who place themselves, unwittingly or otherwise, in a position that enables them to be controlled by others. A wonderful example would be Dustin Hoffman’s portrayal of Raymond Babbitt in Rain Man.
Perhaps this character type has a rosy outlook on life which causes them to be vulnerable, I don’t know, but it helps us to define them. Not being aware of the insidious nature of some people, especially those close to them, makes for a problematic future.
Why do we have them?
My guess, they are to remind us to be on our guard. Not everyone has our best interests at heart and failing to see this can have disastrous consequences. The other reason is to highlight such people in real life. For example, an elderly woman killed herself because she was being pressured by outside agencies. Had someone been there to aid her when she needed it the most, she would not have felt it necessary to use this way out.