De acordo com Harry Potter Wiki , Harry NÃO é exatamente uma Horcrux, mas sim o fragmento da alma, agarrando-se a Harry para a sobrevivência, é um efeito colateral de fazer Horcrux, como Voldermort se tornou "instável". Pode-se considerar isso um fenômeno muito singular.
"Tamper with the deepest mysteries — the source of life, the essence of self — only if prepared for consequences of the most extreme and dangerous kind."
—The first of the Fundamental Laws of Magic To create a Horcrux is to divide one's soul — the "essence of self" — and it is therefore in the creation of a Horcrux that one falls prey to Adalbert Waffling's first Fundamental Laws of Magic, which essentially states that tampering with one's soul inevitably results in grave side effects. Creating Horcruxes is considered one of the most dreadful acts possible.
A third side effect of Horcrux creation is that the master soul itself becomes unstable (even with creating just one Horcrux). The precise dangers of this spiritual destabilisation are not currently detailed explicitly throughout the franchise, however, some can be gleaned from the events in the books.
For example, the creation of Voldemort's sixth "Horcrux" — Harry Potter — is known to be the direct result of this. When Voldemort was hit by the back-fired Killing Curse at Potters' home in Godric's Hollow, it caused Voldemort's soul to split, with one fragment remaining in him and the other displaced part immediately seeking out the only other living thing in the room and latching onto it — Harry Potter. However, this parasitic fragment of Voldemort's soul that attached to Harry was not actually a Horcrux, since it was not created intentionally and the necessary parts of the Horcrux creation process were not carried out.