Why was Claudia helpless? Why did she need a protector in the movie version of Interview With The Vampire?

Vampires (in Anne Rice's works) are both the sum of their human development and the sum of their physical skills and experience they acquired as adults. This is why vampires tended to make vampires of other adults, to expand their support structures and bring new and valuable experiences into their groups aiding in their survival.

What this means for Claudia is:

• Her physical development is stunted. She will have the body of a child, and unable to utilize the full benefit of her vampiric powers that she could as an adult. Nor would she have access to the breadth of knowledge an adult might have had since she did not finish school. All of her learning about the world would be experiential. This is not a terrible thing considering the time, many people learned this way, but she could never take advantage of the opportunity to attend schools of higher learning in the body of a child.

• Her superhuman strength will be proportionally distributed. Yes, it will be greater than a child her size, but will be no match for a vampire who achieved adulthood, the same proportions as a child her age who would fight a human adult.

• Against humans, particularly using the subterfuge of appearing as a child, she does not have any issues of securing prey. Her problem comes in the fact that she is a child and is more susceptible to laws, rules, and controls in modern society. Children wandering the streets after dark may draw more attention to themselves than a wandering adult.

• Yes, she would grow more powerful, as she fed upon the life-forces of humans over the centuries. But in her early years, as an abomination (as far as other vampires are concerned, she would experience no solidarity) she would be vulnerable to predation and destruction since, like other predators, she would be feeding upon the same resources and be considered a competitor; a weaker competitor...

• Vampire culture does not abide weakness, and in an area where vampires dwell, dominance struggles are certain to occur. She would certainly lose such struggles.

• It is implied that Claudia could not make a new Childe. This may be due to the quantity of blood required for a new vampire to consume in order to be transformed. It may require more blood than she will ever have in her body at one time.