RATs frequently contain chat features, both between the hacker and victim, as well as with other hackers. Hacker-victim chat
The main use of a trojan is to play magic tricks upon the victim. Therefore, a RAT will often contain features that allow the the hacker to pop-up a box on the victim's machine, send nasty messages to the victim, and receive responses back from the victim. A hacker really wants to see the expression on the victim's face, but such chat is the next best thing.
Hacker-to-hacker chat
Most infections are wide-open to anybody that finds the victim. Many times multiple hackers will find themselves connected to the same victim. Some trojans allow the hackers to chat amongst themselves. Likewise, this feature allows hackers full anonymity in exchanging information.
