Muggles' Guide to Harry Potter/Characters/Gabrielle Delacour

Overview
Gabrielle Delacour is Fleur Delacour's sister.

Goblet of Fire
We first see Gabrielle when she is one of the hostages for the Four Champions in the Second Task of the Triwizard Tournament. Each of the Champions is given one hour to rescue that which is most dear to them from the bottom of the lake. Gabrielle is what is most precious to Fleur. Fleur fails in her attempt to reach Gabrielle, and is so relieved when Harry surfaces with her that she runs over and kisses him, and also Ron who had some incidental role in her return.

Gabrielle is present in the audience for the Third Task, though she plays very little part. She does wave to Harry, who waves back at her.

Half-Blood Prince
Gabrielle is mentioned in passing by Fleur as part of her planning for her wedding to Bill Weasley along with the fact that she never stops talking about Harry.

Deathly Hallows
Gabrielle is one of the bridesmaids at the wedding of Fleur Delacour and Bill Weasley. She arrives two days before the ceremony, with Monsieur and Madame (Apolline) Delacour, and follows Fleur around, prattling away at her in French and trying to help out. She flirts with Harry by batting her eyelashes, much to Ginny's annoyance. She served as a bridesmaid alongside Ginny.

Relationships with Other Characters
Gabrielle clearly has a strong connection to her sister.