Fleur was aware that in a normal situation, with a normal person, they would blindly take their siblings side. While Fleur was, ultimately, on Gabrielle's side, she was not crass enough tov not see where Tracey's problem was coming from and acted sympathetic accordingly.
"Zhat ees understandable." Fleur assured, running her hand down Tracey's arm before removing it and returning it to lean on the desk. "I'm sure Gabrielle did get somewhere, she always does, but you shouldn't focus on what Heidi did, especially when eet pales in comparison on what she was tempted to do but didn't do." She explained, "considering zhe...charms zhe Delacour women 'old, eet ees truly a surprise zhat she did not go further." Of course, Gabrielle had recounted the tale to Fleur, so she did know the specifics.
Fleur's face became more serious and skeptical of her student. "Gabrielle has led a...privileged life. Our mozher and fazher rarely do not give 'er what she wants. Zhat and her beauty, she ees skilled in manipulating to get her way." In fact, all the Delacours were.
"Our family ees none of your concern, Mademoiselle Davis." She was still suspicious of the girl. "But I can personally assure you zhat Mademoiselle Macavoy was not fully een control of 'er actions zhat night."