High Quality Content by WIKIPEDIA articles! Sofia Vladimirovna Vassilieva (born October 22, 1992) is an American actress. She is best known for playing the children`s book heroine Eloise, in two made-for-television movies, Ariel Dubois in the Emmy-winning TV series Medium, and the cancer patient Kate Fitzgerald in the 2009 film adaption of My Sister`s Keeper by Jodi Picoult.