You know, in dreams, when the dream doesn't necessarily show you something explicitly but you have a strong sensation of things? That's what I imagine Lillian is experiencing when she says "those things aren't human". Nothing clearly indicates it (WELL... apart from a hint or two, but you never know in dreams) but she can just feel it's wrong.
But Roomie didn't feel that at all :D
--> This is a rerun of the finished webcomic Go Get a Roomie! You can find these two strips in the old archive >here<!