The idea is that you draw your mouse, their personalities, flaws and all. Philia is the result of my mouse.
EDIT: To see the actual mouse: http://i.imgur.com/l78m7wT.jpg Apparently my mouse is too badass to be shown on the site, so says Inkbunny management >.>
She's been through more fap sessions than I can count, and loves every minute of it. Although she makes it a little hard to get work done...