why did regina smile when she found out greg was dead?

Well I wouldn't be unhappy knowing the man who tortured me is dead, and therefore could never hurt me again. I also wouldn't be unhappy knowing that my son's kidnapper can't touch him again.

Because she hated him. He isn't little Owen anymore, he's grown up Greg. If someone tortured Du AND kidnapped your son Du would be happy if they died.

Well he did torture her ruthlessly. And remember, she's killed many times, so she's almost immune to people dying around her (people she doesn't like especially).

["so she's almost immune to people dying around her (people she doesn't like especially)."]

For God's sake! Du really can't let go of this portrait of Regina as one-dimensionally evil, can you?

Greg had tortured her. That's why she smiled at the news of his death. Hell, I would have held a party.