Many things could have taken Remus, Sirius knows. A bad moon, a bad wizard, a dark creature or artefact Remus was paid to take care of. It does not quite cross his mind that perhaps Remus is alive, and simply does not want to see him, until he wakes up from another memory-turned-nightmare, where Sirius is yelling and yelling and yelling, saying all these things he means but doesn’t, and Remus, too furious to acknowledge the tears on his face, packs up his things and leaves.