The faint knock would probably not have woken him from his nap on the sofa if Plato hadn't started to bark. As it was, it was the bark that woke him up and got him to realise there was someone there.
'Calm down, Plato,' he said softly, wincing as he forced himself up from the sofa and slowly started to walk towards the door. 'I'll be there in a minute!' he called out, just to make sure whoever it was wouldn't leave.
He sometimes wondered how Percy felt with people coming by as much as they were lately. After all, he wasn't oblivious to how much Percy hated having people in his personal space - his home - yet Cass couldn't get enough of company, and Percy never complained.
When he got better he'd make sure to see his friend in more public places. Spare Percy the inconvenience. He was glad Percy wasn't at home at the moment, it would bother him less if he weren't there.
Finally reaching the door, Cass sighed, leaning on the wall as he opened the door.
'Natalie!' he said surprised, grinning as he let her inside. 'How did you know where to find me?' he asked, smiling as Plato immediately came running to see who the newcomer was