The teaser for Grey's Anatomy Season 21 reveals heightened tensions at Grey Sloan Memorial Hospital following a tumultuous Season 20 finale. Key characters, including Miranda Bailey (Chandra Wilson) and Catherine Fox (Debbie Allen), face off, culminating in a dramatic slap after Catherine belittles Bailey. Meredith Grey (Ellen Pompeo) is set to confront legal challenges from Catherine regarding research she published, while also trying to rebuild her relationship with her son, Jackson Avery (Jesse Williams), who is returning after a long absence. The teaser hints at Jackson's conflicted feelings towards Meredith, potentially indicating he brings troubling news. Additionally, Sydney Heron (Kali Rocha) makes her return, adding to the drama as she interacts with the interns. Fans can expect a mix of confrontations and emotional reunions in the upcoming season, which promises to explore the fallout from previous events.