1: "Grey's Anatomy fans are buzzing about a new theory that may bring Izzie and Karev back in Season 20."

2: "Could a dramatic storyline involving Izzie and Karev's return be the key to Grey's Anatomy's success in Season 20?"

3: "Fans speculate that only a groundbreaking theory can justify bringing Izzie and Karev back in Season 20."

4: "Is there a legitimate way for Izzie and Karev to make a triumphant return in Grey's Anatomy's Season 20?"

5: "A popular theory suggests that Izzie and Karev's return could shake up Grey's Anatomy's Season 20 in a big way."

6: "Will Grey's Anatomy prove this theory true by bringing back Izzie and Karev in Season 20?"

7: "Fans are eagerly awaiting to see if the Izzie and Karev theory will come to fruition in Grey's Anatomy Season 20."

8: "Could this theory be the only way for Izzie and Karev to reunite with the Grey's Anatomy cast in Season 20?"

9: "Stay tuned to see if the Grey's Anatomy theory about Izzie and Karev's return in Season 20 becomes a reality!"