Sophie is seen for the first time in The Confession when Taub has to take care of both kids just after he has to start work with House again. House delights in not giving him a week off so he can make child care arrangements.
In Parents, Taub agrees to take care of Sophie for the night so Ruby can get some sleep.
In Runaways, Taub has trouble connecting with Sophie and Sophia because they're boring. He gets upset when Chase comes over and immediately starts having fun with them. However, he finds a way to entertain both himself and them when he starts making fun of NFL quarterbacks.