Gabrielle is Fleur Delacour’s younger sister, served as Fleur’s designated hostage in the second task of the Triwizard Tournament (GF26).
Harry thought at the time of the second task, when she served as hostage for her sister, that Gabrielle looked no more than eight (GF26).
According to Fleur, Gabrielle talks about Harry all the time (HBP5).
Gabrielle = feminine form of Gabriel (Hebrew, 'God is my strength'); archangel particularly noted as a messenger who heralds and helps interpret dreams and visions. Of the angels associated with the four elements (Earth, Air, Fire, Water), Gabriel is associated with water. This seems apt, given the nature of the second task. -- MLW