Relationships with Other Characters
Rito Yuuki
In the first chapter, Lala only pretends to love Rito so that she can stay on Earth and escape her marriage suitors. However, after he saves her (or rather tries to save her) from Zastin and his subordinates, and reasons the necessity of love and freedom in marriage, Lala mistakenly assumes that Rito truly understood her feelings, and she really does fall in love with him and wants to marry him. It is her marriage to him that will make him the next king of Deviluke, after her father
At first, Lala's love for Rito appears to be childish. She often enthusiastically hugs him and openly shows her affection to him. She claims that he's good "When push comes to shove" (Chapter 5), and believes that he is "The most dependable person in the Universe" (Chapter 19). As the story progresses, Lala gradually matures, and so does her love for Rito, as it is not as insane as before. Her (somewhat) calmer attitude around him has allowed them to develop a closer relationship.
In the last chapter of To Love-Ru, Rito finally confesses to Lala that he loves her. While she is very happy to hear it, she is also overjoyed when he tells her that he loves Haruna as well, believing that he loves Haruna more. In actuality, Lala knows that if Rito marries her, then as the new king of Deviluke, he could also marry Haruna, who has become Lala's best friend. But when Rito's bumbling last attempt to confess to Haruna finds him blindly confessing to four other characters, none of whom were Haruna herself, Lala expresses greater joy of everyone marrying Rito so that they could all stay together, perhaps proving that Lala's maturity still needs to grow some more.
In To Love-Ru Darkness, their feelings for each other remain the same, and they both now enjoy a more calm and comfortable relationship, but they still haven't moved forward into a more romantic relationship, due to Rito wanting to confess to Haruna first, to which Lala encourages. After all the time they had to know each other better, they both now genuinely see something special in each other. When Rito hears about how much Lala loves her sisters, and learns that Lala is truly a kind and pure girl, he falls more in love with her (To Love-Ru Darkness chapter 10). And when Rito goes to comfort and give advice and encouragement to a heartbroken Nana, Lala notices that Nana has cheered up, and she states that it's as expected of Rito (To Love-Ru Darkness chapter 21).
However, Peke wondered that if it's ok to leave her where it is now, saying that there hasn't been any real development since Rito's confession to her and also says that it's not enough. With some encouragement from Momo (and for the sake of completing her Harem plan), Momo tells her to be more appealing towards Rito. Lala starts acting like her old self and being really clingy to Rito again. Lala also teleported into the bathtub where Rito currently was (reflecting the time first they met). She started coming onto him and even wanted to try a kiss. (To Love-Ru Darkness chapter 34)
After an ecchi moment in the bathroom, Lala practices kissing Rito with the stuffed bunny he gave her, when Nana walks in and Lala tells her about Rito's feelings. The next day, Rito confronts Lala on top of the school and admits that he can't kiss her until he's figured out his feelings, something Lala has expected, since Nana told her the previous night. She then apologizes to Rito for loving him so much she didn't realize his feelings. She then proceeded to kiss him on the cheek and states that until he's ready, she'll be waiting for a special kiss from him. (To Love-Ru Darkness chapter 35)
Haruna Sairenji
Lala regards Haruna as her best friend and will often go to her for advice when she is not sure about some part of Earth culture or Rito. Later, Haruna reveals to Lala that she too is in love with Rito. This causes Lala guilt over how she has acted around Rito over the previous year; she even tries to distance herself from him in an effort to make Haruna feel more comfortable.
Later, after much thinking, she confronts Haruna and declares herself her official love rival. She has since reverted back to her over-the-top method of displaying her affections to Rito.
After Rito confesses to Lala that he loves both her and Haruna, Lala becomes overjoyed and encourages Rito to get together with Haruna. In truth, Lala's real desire is for both Haruna and herself to marry Rito, which will be possible if Rito marries Lala and becomes king of Deviluke, making polygamy possible for him. Lala also tries to encourage Haruna to confess to Rito, but Haruna is too shy to and doesn't understand Lala's reason for being so supportive until Momo explains to her that both she and Lala can marry Rito. Currently, Haruna doesn't quite know what to make of this newfound possibility.
Peke
As Lala is her creator, it goes without saying that Peke is greatly loyal and obedient to Lala. Peke is Lala's most constant companion, and has been with her since her creation and when Lala ran away from home. While Peke considers Lala as a great person, admired for her beauty and intelligence, and finds any suitor unworthy of her, Peke is still aware of some of Lala's eccentricities. She questions Lala's judgement in choosing Rito as her fiancé, and her childish attempts at getting closer to him. And she says that despite being one of the greatest geniuses in the galaxy, most of Lala's inventions turn out to be pranks.
Nana Aster Deviluke
Nana is one of Lala's little sisters and has shown very high respect for her sister, calling her "Ane-ue". They both excel in sports, and sometimes Nana would get a little upset with her for her airheaded personality. Nana also shows respect for her when she scolds Momo for sleeping in Rito's bed, saying that Rito is Lala's fiancé.
Momo Velia Deviluke
Momo is Lala's youngest sister. Like Nana, she also shows high respect for her older sister, calling her "Onee-sama". Momo's respect was also shown when she did not try to steal Rito from her, and instead decided to be contented with being a lover. However, Momo has since found a compromise so that her sister would not be heartbroken, and Momo's love for Rito can still be reciprocated.
In To Love-Ru Darkness, Momo inherits and expands Lala's harem plan, wanting to share Rito with her sister, as well as with all of Rito's other love interests.
Mikan Yuuki
Lala thinks very highly of Mikan, mostly because she lets her stay in her and Rito's house and Lala loves her cooking. Lala and Mikan are very good friends and Lala always tries to help her with chores (even though she messes up the chores most of the time). Their relationship at times can even be described as siblingly.
Mikan is somehow extremely casual and unfazed with the eccentricities around Lala, whether it's Rito's recent engagement to Lala, or even Lala's alien origins. Even finding Lala completely naked in Rito's bed has become a normal occurrence to her. Mikan easily welcomed Lala into their lives and is pleased to know that things will get more interesting upon Lala's arrival. However, she does not feel the same way about her sister Momo, who is more mature and mischievous.
Lala really enjoys Mikan's cooking, which she is really terrible at, always putting dark matter in it.
Golden Darkness (Yami/Eve)
Lala considers herself a friend to Yami, going so far as to help her pick out new clothes (Chapter 61), and help Yami realize how nice Rito really is by letting Mikan and Yami switch bodies for a while (Chapter 139). Yami would even put aside her hatred towards Rito for the moment whenever Lala asks her.
It was Lala who named her Yami-chan, a name repeated by most other characters.
In To Love-Ru Darkness, Yami's Darkness transformation activates, radically changing her personality. With her newfound shameless personality, she psychotically expresses her love for Rito and her desire to kill him, and with Lala protecting Rito, Darkness declares Lala as her enemy and the one blocking her from killing Rito and become one with him.
Yui Kotegawa
Lala and Yui's relatively identical figures in contrast of their opposite personalities.
In terms of personality Lala and Yui are polar opposite of each other. But in sprite of that they are generally friends, even though Yui does hold some dislike over Lala's naive, yet indecent behavior.
Lala likes Yui a lot and often tries to find ways to include her into their group events. While others have a tendency to view Yui in a bossy, and sometimes resentful light, Lala does not. However, due to Lala's nature, it is doubtful if she would see anything as bad in her.
Regarding appearance Lala and Yui sports nearly identical curvaceous figures and together are considered to have most attractive bodies on school by others girls. Whenever a comparison of girls' figures is brought up Lala and Yui are often used as sort of ideal that other girls want to achieve. Ironically, even though these two have the best bodies, they are the only two so far who pay no real attention to their appearance.
Yui would seemingly get jealous whenever she see's Lala close to Rito, but naturally denies it herself.
Ren Elise Jewelria
When they were children, Lala would often dress up Ren as a girl and call him a cry baby. Lala would also perform disastrous experiments on him and test out her inventions on him. Despite this, Ren is in love with Lala. In their past, when Ren asked Lala if she would marry him, she passively replied that she would if he could become manly. Upon arriving on Earth, Ren persistently tries to prove to Lala that he has become manly by trying to defeat Rito in various completely pointless challenges. However, Lala remains passive, neglectful, and even somewhat oblivious of Ren's attempts to court her, as she now only wants Rito.
Run Elise Jewelria
Run is Ren's (former) female self, who is essentially an entirely different person but shares the same body as Ren. While Ren is in love with Lala, despite Lala playing with them quite abusively as children, Run holds a grudge against her. She never forgave Lala for tormenting her as a child. To make things worse, Lala has Rito, whom Run is also in love with. Run immaturely made various outrageous attempts to get revenge and harass and humiliate Lala, such as using the youth skunk and the clothes-destroying bomb, but they all backfire. But Run and Lala are actually friends, and have been since childhood, and Run doesn't genuinely hate Lala, but simply has been angry at her. Lala still regards Run as one of her best friends and is completely clueless about how Run feels.
In recent times, Run has had a more friendly relationship with Lala, or at least more civil, and seems to have put her grudge behind her, as she no longer tries to get back at her by pulling pranks on her. After Run becomes a popular idol and attends school less often, she and Lala are rarely seen together anymore.
Saki Tenjouin
While Lala tries to be friends with everyone, Saki Tenjouin holds a grudge against Lala for challenging her popularity (without being aware of it). Saki used to be the most popular and beautiful girl in school, until Lala showed up and attracted all the attention away. Saki goes so far as to go naked, set up booby traps, and even shoot Lala with mustard to try to humiliate her. Most of her antics usually backfire. However Saki has shown some gratitude when Lala helped her the time she ran away from home.
Lala is mostly oblivious to the fact that Saki really doesn't like her, and is still friendly to her.
Risa Momioka & Mio Sawada
Risa and Mio are Lala's somewhat perverted classmates and friends of Haruna. Lala has limited direct contact with them in the series but clearly enjoys their company. Indeed when the two of them engage in their usual antics of groping girls, Lala is never annoyed by them, even when it's her turn to be groped.
Mikado Ryouko
"Mikado-sensei", as the kids usually call her, is one of Rito's and Lala's personal friends. When Lala had her strange flu, it was revealed that Mikado is in fact also an alien and provides exotic herbs and treatment methods intended for other aliens that live amongst unknowing Earth inhabitants.
Lala is respectful of Mikado and treats her with the same sunny personality that she treats everyone else.
Gid Lucione Deviluke
Her father, the King of the planet Deviluke, can be very strict and demands obedience from Lala and her sisters, like when she ran away from home to escape meetings with her suitors (which he forces her to go to), he sent extreme forces to bring her back.
In the manga, he seemed kind and understanding of Lala's choice in having Rito for a husband and said to arrange the wedding right away, but she declined his wedding plans, making him go back to being strict, stating that he finally allowed her to have her own way, but she revealed that he only wanted her to get married so he can step down as king and go around doing perverted things (also because she knew that Rito did not love her at the time and did not want to force him).
She is shown, however, to have warm memories of him from her childhood, comparing Rito's kindness to her father coming to find her when she was lost in the woods on Deviluke.
Sephie Michaela Deviluke
Sephie is the mother of Lala, Nana and Momo, and she has yet to make an appearance in the manga. Peke notes that Lala's mother is very beautiful, and that Lala has inherited her beauty and attractive physique from her. Momo states that she's a wonderful person. As the current queen of Deviluke (in their father's place, who isn't good at politics), she demonstrates active leadership and endeavors to maintain relations with every planet. To Lala and her sisters, she is the person they admire the most.
Momo has stated that despite being busy most of the time, their mother still makes time to call them (To-Love-Ru Darkness Chapter 23). She finally makes time to visit her daughters after hearing that Lala became small after overusing her powers.