 Thatcher and Susan Grey ( Jeff Perry and Mare Winningham ) , Meredith 's estranged father and step @-@ mother , are introduced in season two , with Susan making appearances until her death in season three , and Thatcher continuing to appear on the series . Adele Webber ( Loretta Devine ) , is introduced as Richard 's wife , who eventually acquires Alzheimer 's , in the seventh season , and continued to make appearances until her death in season nine . Introduced as Preston 's mother , Jane Burke ( Diahann Carroll ) makes occasional appearances until the fourth season . Denny Duquette ( Jeffrey Dean Morgan ) , a patient suffering from congestive heart failure , originates as one of Burke 's patients , who goes on to propose to Stevens , after weeks of bonding between the two . Facing death , Stevens cuts Duquette 's left ventricular assist device ( LVAD ) , to elevate his position on the United Network for Organ Sharing ( UNOS ) transplant list . This ultimately ends in his death , marking his initial departure from the show , and placing Stevens on disciplinary probation . Initially conceived as a veterinarian hired for Shepherd 's dog , Doc , Dr. Finn Dandridge ( Chris O 'Donnell ) soon becomes a love interest for Meredith , while Shepherd is with Montgomery . Dandridge is included in a multi @-@ episode story arc , consisting of nine episodes , ending when Meredith reunites with Shepherd . 
