Philotes was only there as a look out. She hadn't played any part in the capturing of Patroclus... She was very confused when she saw a second person... Someone else? There was no time to make small talk over who the second person was so she just leaned against the wall next to the door and waited patiently. She knew this was the worst idea ever, but maybe her mother would get wind of it and be proud of her! That would make it all worth it.