Isabel joins Pam and Jim at their wedding. She meets Dwight Schrute and has sex with him, however, Dwight doesn't want to continue. She tells Pam that she is seeing Dwight, to which Pam is shocked, and accidentally tears her veil. ("Niagara")
She visits the hospital to see Pam and the newborn baby. She also visits the Halpert home and encounters Dwight. ("The Delivery") When Pam, who has been on maternity leave, invites Isabel to happy hour, she and Dwight make out despite his pre-natal contract with Angela Martin, who follows them. When Angela tells Isabel that they are having a baby, she doesn't care, taps Angela on the forehead, as in "whack-a-mole", and leaves with Dwight. Angela decides to take Dwight to court. ("Happy Hour")
She is possibly named after Paul Lieberstein's (who plays Toby and is the former show-runner) wife, Janine Poreba.