'Grey's Anatomy': Why Ellen Pompeo Returned for Season 20 Premiere

Ellen Pompeo is back! On the 'Grey's Anatomy' season 20 premiere, Meredith Grey returns to Grey-Sloan with Catherine Avery after the two attended a benefit in Boston, where Meredith now lives. But Catherine isn't happy with Meredith after she announced that she planned to pursue alternative causes of Alzheimer's and not just the ones Catherine was helping to fund her research. 'Grey's Anatomy' airs Thursdays on ABC.