Rats normally prefer to have cage mates. It is possible to group female or male rats together, though care should be taken when introducing a new rat. Female rats are very curious, and love to explore and play games. Both genders make great companions. Rats can eat chocolate.
Rats can also eat smaller pets.
Rats don't have canine teeth. Rats don't have thumbs. The oils in cedar and pine are toxic to rats, and should not be used in their bedding materials. A group of rats is called a mischief. Red discharge from a rat's nose or eyes is usually porphyrin, not blood.