Lily was born in Vietnam and was adopted as a baby by Mitchell and Cameron.
Mitchell originally wanted to wait to tell the extended family that they had adopted Lily. However, Cameron knew Mitchell will shy away from introducing her forever, so he plans a surprise dinner where he introduces the baby in a Lion King manner. The family welcomes her with open arms, even Mitchell's dad Jay. She is, at times, doing activities with both of her fathers, but remains with Cam at home while Mitchell works.
Cameron often dresses her up as celebrities, such as Diana Ross, Madonna, and Ray Charles for the purpose of taking photographs. Cameron and Mitchell are currently practicing the Ferber method on Lily but Cameron can't always resist catering to her during the night, sometimes even watching movies such as Scarface, which Cam claims she likes possibly because of the bright colors, particularly the club shooting scene.
Another noticeable thing about Lily is that in most episodes she appears in she is seen with "Doggy," her stuffed dog, which appears to be a Labrador. She is a quiet and peaceful baby when portrayed by infants Ella and Jaden Hiller, and does not speak for the first two seasons.
Lily is no longer played by babies Ella and Jaden Hiller, but instead by bubbly preschooler Aubrey Anderson-Emmons. She now begins to talk and becomes a full-fledged character. She is vocal about not wanting a new baby brother, and is shown to have some other faults typical of toddlers, such as difficulty with sharing.
Mishaps with LilyEdit
There have been several occasions in which Lily has been involved with and/or caused a problem during an episode.
During a Hawaiian vacation, Mitchel and Cameron get into an argument that continues when they leave the elevator– and neither of them pushes the baby carriage out with them. Luckily Gloria finds a run-away Lily on the first floor.
Run for Your WifeEdit
Cameron had finally convinced Mitchell to dance with Lily. Of course, Mitchell accidentally hits Lily's head on a door jamb when he throws her up in the air. After quite a bit of fussing, more by her fathers than by herself, Mitchell and Cam finally decide to take her into the doctor. It turned out Lily was fine, but it wasn't long before the next little incident occurred.
Planes, Trains and CarsEdit
In the episode, Trains, Planes and Cars, Mitchell and Cameron lose Lily's favorite stuffed bunny on the subway. She keeps Mitchell and Cameron up all night and they try to tell her that her bunny went to a magical land and to sleep with a different stuffed animal. That doesn't work either.
Little Bo BleepEdit
In this episode, Lily discovers that cursing (particularly using the F-word) can elicit laughter from her daddies, so she repeatedly drops the F-bomb as Cam and Mitch try to teach her not to say it. The episode culminates with Lily loudly shouting the profane word while she is a flower girl at a wedding.
In "Disneyland", it is revealed that Lily is a "runner". Cam and Mitch try to keep her from straying from the family but it is to no avail; she dashes off at every opportunity, much faster than her daddies can catch her. Finally, Cam resorts to putting a leash on her, though Mitchell can feel other parents judging her. Their parenting problem is solved when Jay buys Lily a pair of baby high heels, in which she has no choice but to pick her way along slowly and carefully.