Is it possible to add audio files on your pet profile? I'm afraid the answer is no but if yes then I'd love to have one of these voicelines on my fan Brightwing's profile!

I don't think there's a way to do this (and it might be removed even if you found a way around it). In the past, staff prohibited any kind of music on pet profiles because they didn't want people attaching midi files/etc to them. It'd also be too easy to get around the content filters if it was allowed.