Peke is a small sentient robot created by Lala Satalin Deviluke to serve as her personal clothing system. It functions as an all-costume module, meaning it can transform itself into any outfit Lala needs, effectively acting as both a portable wardrobe and a wearable garment. In its resting state, Peke usually sits on top of Lala's head in the form of a hair pin, which makes it one of the most constant presences around the Deviluke princess. Its most recognizable physical traits are its spiral-shaped eyes and the small wings on its back, and its gender is not clearly defined within the series.

Peke's entire existence revolves around Lala. It was built by Lala to be her clothing companion, and it is exceptionally devoted to her, serving as her most loyal and ever-present assistant. Although it is a machine, Peke displays a surprisingly broad range of emotions, including joy, anger, and sadness, which makes it seem more lifelike than a typical robot. In the earlier parts of the story, Peke could come across as somewhat sarcastic, but overall it is polite, attentive, and sincere in carrying out its duties. Its main motivation is simply to serve Lala faithfully, keeping her dressed, assisting her whenever she needs an outfit, and standing by her through the everyday chaos of life on Earth.

Peke's defining ability is shapeshifting. It can transform into clothing pre-set by Lala and can copy any type of clothing it has seen, giving Lala a virtually endless wardrobe on demand. This power comes with a limitation: using it drains Peke's battery. As its energy runs low, whatever clothing it is maintaining slowly dissolves and eventually disappears, which often leaves Lala exposed at inconvenient moments. Peke recharges by sleeping, and if it does not get its nightly rest, it loses power altogether and can no longer keep Lala clothed. In addition to its transformation ability, Peke is a talking robot that communicates regularly with Lala and those around her, sometimes offering commentary on the situations the group finds itself in.

In the story, Peke functions as a supporting character tied directly to Lala. It is the reason Lala can change outfits instantly, and its power failures are a recurring source of comedic trouble. It is also occasionally caught up in the side effects of Lala's inventions; in one notable incident, one of Lala's devices causes Rito to become merged with Peke, making the pair share the same body for a short time. Such moments show Peke being drawn into the larger cast's adventures even though it has no ambitions of its own.

Peke's most important relationship is with its creator, Lala. The bond is one of deep loyalty and constant companionship, and Peke is almost never seen apart from her. Through Lala, Peke also comes into contact with Rito and the other main characters, though its direct interactions with them are usually brief. It can also serve the people around Lala in a practical sense when it produces outfits for them, but its emotional attachment is reserved for Lala.

In To Love Ru: Darkness, Peke's role becomes noticeably smaller. Because the sequel shifts its attention toward other characters and plotlines, Lala appears less frequently, and Peke's presence shrinks along with hers. When Peke does show up, it rarely speaks, remaining a quiet background presence rather than the chatty companion it was in the original series. The character does not undergo any significant development or change during Darkness; Peke remains what it has always been, a devoted and hardworking costume robot whose loyalty to Lala never wavers.