Maybe under different circumstances - if, say Severus were under the influence of a befuddlement draught - he might have been willing to hear Remus out, might even be willing to believe him. As it were, not being under the influence of questionable potions, Severus was entirely unmoved by Remus's words - having had to come to grips with an attempt on his life made the whole thing rather difficult for him to accept.
He snorted, refusing to lower his wand, "Right, I have every reason to believe you, because you have such a wonderful track record of standing up to those two."
The full horrifying truth was starting to sink in, and it was just one more reason for Severus to hate his life.
They were flatmates?! Were they paired up becaus the powers that be thought 'hey, they came from the same place so they must enjoy each others company'? This was some joke, is what this was - a terrible cosmic joke.
Severus gave a quick glance behind him, focusing on the door furthest from the one Remus indicated - Severus chose that for his room - if he was going to be stuck in this flat with Remus Lupin he'd stay as far away from the prat as possible. He took a step back in the direction of the room he'd chosen.
"Really, Lupin, considering the past, I don't think you are the one that should be afraid of murder."