Every superhero has their key love interest; Superman has Lois Lane, Spider-Man has Mary Jane Watson, Hulk has Betty Ross, Iron Man has Pepper Potts, Batman has Catwoman, Thor has Jane Foster and Mister Fantastic has Invisible Woman, just for a few examples. For Doctor Strange, it's Clea - an inhabitant of and sorceress from the Dark Dimension. She would observe Doctor Strange from there under the orders of Strange's arch-enemy and her Uncle Dormammu, but became impressed by his courage and tried to warn him about Dormammu's evil intentions. She would be held captive in a pocket dimension as punishment, but she was rescued by the Ancient One, sent to Earth and ended up living and falling in love with the man she was originally meant to be an enemy of.