Who is Princess/Counselor Leia Organa Solo from Dark Force Rising and what is their importance?

Princess/Counselor Leia Organa Solo is one of the only survivors of Alderan. She and Luke Skywalker were twins, but they were separated at birth and have only recently been reunited. Leia is married to Han Solo, but she doesn't spend a lot of time with him, as she is engaged in assisting in matters of state. She is currently pregnant with twins and is in danger of being kidnapped by Master Joruus C'baoth.