Sylvia is a cave girl from 12,000 B.C. She doesn't speak english- her language is represented to the reader through emojis. Her lines are largely up to interpretation- grunts and other vocalizations are primarily what her lines will sound like. 

Generally, Sylvia is a very cheerful person. Her favorite thing is food- she'll do practically anything for it. She displays incredible strength, and is physically the strongest character in the comic. She has a carefree attitude and won't hesitate to protect her friends- even if it means giving up her own life.