<Li> Jay Ali as Timothy (season 1 - present): Callie's and Talya's literature teacher . They call him by his first name . He was Stef and Lenas' new baby's biological father before the baby died due to pregnancy complications . </Li> <Li> Mary Mouser as Sarah (season 1 - 2): A foster child in Callie's foster child support group who was staying with Liam and his family . Callie became worried for her safety upon learning Liam was with her . She was then taken out of Liam's home after Callie confessed to Lena and Stef about Liam assaulting her . </Li> <Li> Sam McMurray as Frank Elkin (season 1): Stef's late father, who struggled to accept Stef's relationship with Lena . He dies in "Family Day", deeply affecting Stef who regretted never making amends with him . </Li> <Li> Annie Potts as Sharon Elkin (season 1 - present): Stef's supportive mother and ex-wife of Frank . </Li>

Who plays aj's brother in the fosters