I don’t recall that he ever mentioned having a last name, or that he took on Marius’ last name at any point…
[^X Björn by gampy (Björn is a fandom fave for Armand)]
Opening this up to anyone, was Armand ever given or has he ever mentioned taking on any specific last names? I can’t even think if he’d ever shared aliases, as Lestat often does…
I got some good responses to this post, you can peruse them, and whether you agree that “le Russe” is Armand’s last name depends on whether you accept PL as canon.
Others noted that it’s Ivanovich, because his father’s name was Ivan. As far as I know, that’s the naming convention in that part of the world, that your last name includes your father’s name like that, but I didn’t see “
Ivanovich” explicitly written in canon. At any rate, Armand is no longer “Andrei,” so I wouldn’t think that he would have kept that last name, either.