Who knows? Does Armand himself know? Had Marius came up with some date as well as with the name? Fandom (at least part of it), as it seems, picked 11th November and celebrates it in RP.
//I believe, as with Lestat’s bday and Louis’, it’s a thing AR stated somewhere. Anyway, those are interesting questions. Armand probably would not know, specially because kids bdays were pretty much not a thing, so it’s unlikely the date was important in any way. On the other hand, with how much people liked astrology in Venice it’s possible they had picked a day for him? (Maybe Bianca did it xD) Maybe Marius would have liked to celebrate the boys bdays somehow? Interesting to consider.
#Headcanon Accepted
…and it would also aggravate Armand to no end that everyone tends to make such a big deal for Lestat’s birthday 4 nights before his bc otherwise the Brat Prince throws a royal tantrum. The one-upmanship never ends.
I-want-my-IWTV 