(3 point Merit)
Most people only see their Avatar during Seekings, if at all. Your mage's drops by every day for tea, if it doesn't hang out 'round the clock. This Avatar is completely invisible to everyone but your character (and those who can read her mind), unless you take this Merit in combination with the Background: Allies Background, creating the body of a person or familiar for your Avatar. In this case, your Avatar becomes your bamf!ing buddy, popping in and out of existence when it feels like it. If it's killed, only the mortal shell dies, not your Avatar--unless you also have the Flaw: Phylactery, in which case your Avatar's form is immune to all physical harm, but is manifested permanently. If such is the case, it is able to be kidnapped, transformed and so on.
Storytellers should note that an Avatar doesn't have to say it's an Avatar, and just because an Avatar in invested into a phylactery doesn't mean everything that phylactery tells you is a pronouncement from your Avatar. A V-A may have his laptop as a phylactery, but unless he's also taken Manifest Avatar as a Merit, his laptop's warnings to update his virus software are nothing more significant than that. Likewise you may have invested your Avatar into your best friend, but that doesn't mean that everything (or anything) he says are pronouncements from your personal spirit guide. Such only happens to be the case if you take Manifest Avatar. Even then, why should your Avatar tell you he's anyone except your best friend?
A manifest Avatar can chat with you and other people like the intelligences that show up on the Web to guide Virtual Adepts and converse with their contemporaries. With the right tricks, it can even materialize to harangue you, to fight, to push you around or just make for a hot date.