There's some slight variation, but the general idea is that if you tell them what your name is, that's dangerous. If they just overhear it from someone else, then I don't think they can use it the same way, but I would not exactly want to gamble on that.
Yeah it varies but commonly "giving" then your name allows them to assume your identity and "telling" them your name allows them to assert control of some kind over you
sometimes there is also a defense in being more sure of your identity and selfhood than the faeries can deal with but that's generally more modern stuff
There's a running gag in the trans community that most of us would love to meet a fae and then sell them our deadname. Go ahead, be the person I no longer want to be, I'll be myself whole and entire.
"Eric"
login informationTrue Name, I can take on your identity and steal your powerbut that's generally more modern stuff