What happens to adria in diablo 3?

Answer 1

In Act I, it is believed that Adria is dead. The cultist leader, Maghda, reveals that she is alive, and about to be captured by her forces.

In Act II, she has been captured by Belial's servants, but is freed by the player. Through her help, during Act II and Act III, the player and Leah are able to seal the two remaining lesser evils into the Black Soulstone.

However here she betrays you, saying she was the one who knew Diablo possessed Leah's father, that she was the one who sealed the other five evils into the soulstone, and that it was all to resurrect Diablo using Leah, as a united 'Prime Evil'. Diablo dismisses her until such a time he needs her services again, before he launches his assault on the High Heavens.

It is implied also that Adria was the joint leader of a Belial-worshipping cult, along with Maghda, however it was Diablo who called to her and got her to leave, she travelled to Tristram to aid the player in the original game, who has retroactively been named Prince Aidan, Leoric's elder son, Diablo's host, The Dark Wanderer, father of Leah.

Adria does not appear in Act IV. So her current status is unknown, but clearly, this is their setup for an expansion.