My group left the game last week in a tight spot. At the beginning of the encounter, a half-elf PC failed her save against a Vampire's charm – even with advantage, thanks to the half-elf's racial Fey Ancestry trait:
You have advantage on saving throws against being charmed, and magic can’t put you to sleep.
The vampire's charm effect states:
Charm. The vampire targets one humanoid it can see within 30 feet of it. If the target can see the vampire, the target must succeed on a DC 17 Wisdom saving throw against this magic or be charmed by the vampire. The charmed target regards the vampire as a trusted friend to be heeded and protected. Although the target isn't under the vampire's control, it takes the vampire's requests or actions in the most favorable way it can, and it is a willing target for the vampire's bite attack.
Each time the vampire or the vampire's companions do anything harmful to the target, it can repeat the saving throw, ending the effect on itself on a success. Otherwise, the effect lasts 24 hours or until the vampire is destroyed, is on a different plane of existence than the target, or takes a bonus action to end the effect.
Cut to the end of the fight. The charmed character is unconscious. She was taken down by the Vampire's summoned wolves, had two failed death saves, and then rolled a nat. 20 on her turn, coming back with 1 HP. I'm going to give her a chance to make her save against the charm effect again when the session starts on Thursday.
By RAW, does Fey Ancestry give advantage to a charmed character making the save to break the charm effect?