What is all this from?Although the Patronus in some ways represents your individuality and personality traits, Tamske is quite right to assert that in essence, a Patronus is the embodiment of the most secure time in your life, and/or your basic survival ‘(animal’) instinct. An example of why it cannot possibly be considered to fully represent a person’s essential character is in the case of Remus, whose worst fear is the moon, and thus his Lycanthropy. If his Patronus represented his character, it would be difficult to imagine that it would embody something which his heart fights so hard against, and his Patronus would be something much gentler and more peaceful. The reason why Remus’ Patronus takes the form of a wolf is because regardless of how he feels about it, the wolf/werewolf is his basic survival instinct.
It is also possible that the trauma of being bitten at such a young age caused his Patronus to change into the only creature that could have protected him at the time, had it called Greyback away-a werewolf. However, since lack of life experience and power prevents such a young wizard from casting a fully corporeal Patronus, this would be impossible to confirm either way. The case of Harry is very similar, as since Patronus form is not hereditary, it is possible that the unconscious trauma caused by the murder of his parents forced his Patronus to take the form of his least vulnerable protector- his father, in a bid to almost subconsciously compensate for his loss. Since the Patronus is also largely based upon strong positive emotion to counteract the draining power of the Dementor(s)/ Lethifold(s), the Patronus can also represent (apart from in the case stated above) a time when a person felt most peaceful (for Harry this would be with his parents)
Other characters that suffer great trauma have this reflected in their Patronus, again as a sort of coping mechanism for loss of a beloved protector. Going chronologically, Snape’s beloved protector was Lily, who tirelessly attempted to put an end to his bullying, regardless of the fact that she knew he might turn to Voldemort after school. When his love got too hard for him to bear and he lashed out at her in an elitist manner, she cut all ties, and he had to watch James, his rival win her heart. He lost her completely, breaking his heart and changing his Patronus.
Tonks has/had two beloved protectors with similar Patronus forms, the people whom she lost (or thought she lost) within a fairly contained period of time. She of course was very close to Sirius, and the joint devastation of herself and his best friend brought them together, yet still her Patronus did not change at this point. The catalyst for her change of Patronus was Remus rejecting her love initially, because he thought he posed too much of a threat to her in his Werewolf state, and was worried about causing a rift between herself and her family, hence again, the Patronus took the form of the desire to bring back the protectors who made her happiest, as with Harry and Snape.
In conclusion, the Patronus of a wizard/witch with a fairly uncomplicated life would take the form of whichever animal your subconscious would feel most comfortable being protected by (Which is where the 16 MBTI types might come into play.) Since no wizard/witch has exactly the same Patronus form, the individualistic part, influenced by your personality, would manifest in how your Labrador (example) looked very different from every other Labrador Patronus ever conjured.
Sorry that was so long....I am not sure if you can relate to it, but please feel free to comment :-)