Dr. Lopez is first mentioned in "Overnight Success" by Harold McBride. When Howard is hesitant to let Clyde spend the night at Lincoln's house, Harold reminds Howard about how Dr. Lopez encourages parents to "let go" in such situations.
In "Two Boys and a Baby", Clyde mentions that Dr. Lopez has an extensive selection of magazines and books in her lobby. He is particularly interested in the books about how to take care of babies. Four of the book titles are Food for Tot, NapQuest: The Impossible Journey, Take a Walk on the Child Side, and Oopsie, My Baby Made a Poopsie.
In "Save the Date", Clyde is distressed after seeing Lori and Bobby together. He calls Dr. Lopez, telling her that it is a "Lori emergency," but is interrupted by Lincoln. Clyde calls her again at the end of the episode.
In "11 Louds a Leapin'", Howard starts to cry tears of joy after seeing Mr. Grouse and Lincoln as friends. Harold tries to remind him about "what Dr. Lopez said", (presumably something about controlling his emotions) but realizes that the moment really is too beautiful. He says to Howard, "Oh, forget about Dr. Lopez! This is the most wonderful thing I've ever seen!", as they walk off screen.
"Brawl in the Family" is Dr. Lopez's most prominent episode yet, since there is an entire scene in which Clyde dresses up as her and pretends to be Lincoln's therapist. In this scene, he says that Dr. Lopez helps him by listening to his problems as he lies down on a couch. It is also shown that Clyde's meetings with Dr. Lopez are timed, and that she has a watch that tells her when the session is over.
In "Making the Grade", Clyde books an appointment to see Dr. Lopez after he could not sit next to Lincoln in class, but afterwards, he cancels the appointment when Lisa declares that she is going back to kindergarten.
In "The Whole Picture", Clyde tells Lincoln about the "steps of healing" that Dr. Lopez taught him.
In "ARGGH! You For Real?", Howard wants to call her but Harold tells him not to because he stated that she and Robert are trying to make their marriage or relationship work.
In "Lynner Takes All", when Lynn asks if her siblings know any good therapists, Lincoln tell her that Clyde recommends Dr. Lopez, but Lynn cuts him off.
According to his bio, Clyde's idea of a perfect day would include a zombie movie marathon with Lincoln, a picnic with Howard and Harold, and a double-session with Dr. Lopez.
One of Clyde's quotes in the Cartoon Creator game is: "Dr. Lopez? Do you have any appointments this week?"
Dr. Lopez and Clyde are apparently very close. Clyde knows her phone number and calls her whenever he comes across a "Lori emergency".
Howard and Harold
Dr. Lopez has met Howard and Harold. Whenever Howard starts to get emotional about seeing his son Clyde grow up, Harold reminds him about Dr. Lopez's teachings.
It is unknown whether or not Dr. Lopez has met the Louds. However, Lincoln knows who she is, probably due to Clyde mentioning her often.
Although it is unknown what Dr. Lopez looks like, Clyde dresses up as her in "Brawl in the Family" and gives the viewers an idea of how she dresses. Judging by his outfit, she wears brown shoes, a green overcoat, and a yellow scarf.