These two came together when Louis and Claudia went to Paris to seek out others of their kind. Armand gave the order to terminate Claudia’s life though Louis didn’t know that until Lestat told him after Louis had been with Armand for a hundred years. Armand was attracted to Louis because of course he was beautiful but also because of Louis’s mercy because he was “an immortal with a mortal’s passion”. Their relationship is seen almost completely in Interview with the Vampire
Louis blamed Armand for his losing Claudia but after that seemed only to blame Lestat, as he blames Lestat for everything. Louis still loves Armand as we can see when Armand goes into the flames at the end of Memnoch the Devil and he is relieved when Armand is all right. One wonders who Louis loves more; Lestat or Armand. The answer should be Lestat since Lestat is his maker. But Armand’s selfish mistake is killing Claudia shouldn’t go overlooked, as it often is in Louis’ judgment.