Ancients are basically the oldest elves that currently live. They usually have pointed ears as a sign of maturity/age, first stated in the first book. They rarely accept visitors in their solidarity lives, because they've been through so much more than others that it's hard to relate.
Vespera: She was alive when humans still lived in Atlantis, and Fallon was a Councillor. She has a history of being a prisoner in Lumenaria, washed out of the councilor's minds, and generally causing havoc for Sophie and her friends to fix.