In chapter 3 of War with the Ice Lady is where we first meet Vincent:
'The twins made a small fire. After snacking on some nuts, berries, and bugs, they laid down to rest.
A weird noise disturbed Gloria. Startled, she stood up on her hind legs quickly and looked around. She was ready to defend herself when she she heard a voice say, “What is wrong with you? I was only trying to stay warm by your fire. Is that a problem? If there is a problem I will certainly leave. I don’t want to leave because it is so warm here. Tell me if I can stay or or or not stay.”
Gloria looked down where she thought the big voice was coming from. She expected some strange animal that she had never encountered before, but lying next to the fire was a frog. He was larger than most frogs. His height almost reached Gloria’s waist.
Gloria asked the frog, “What is your name and where have you come from?”
The frog responded, “My name is Vincent. As you can see, I have grown so very large. The other frogs did not want me to live with them, so I traveled north to make a new home and new friends.”'