Ralph is a grey adult male mouse who wears glasses, a green business suit with a green button down collared jacket and green dress pants and a white collared shirt, dark grey necktie, gold necktie clip, and a folded light blue hankie in his pocket, and black dress shoes.
According to the model sheets, he is roughly 6 ft tall.
Ralph is mild-mannered, kind, considerate, and thoughtful.
Princess Carolyn has stated that he was the only guy she ever dated who never considered to be "an asshole."
Ralph was always considerate, about her thoughts and feelings, but was well aware that she could be stubborn; or not always have the right answer. Ralph wishes she would occasionally listen to what he has to say, even though he is still open, for her rebuttal opinion as well.
Ralph Stilton was introduced in Love And/Or Marriage. Princess Carolyn had the night off for once, and jokingly asked her assistant, Judah, to get her three dates. He actually does, and she decides to go through with it, as she can't reschedule any of them due to her busy life running VIM.
Her first two dates don't work out until she meets Ralph, a mouse. When he meets her and she groans at this, he jokingly says "I think I know how this ends," and the two laugh. Princess Carolyn is about to leave when Ralph offers to take her to another restaurant that does good cheese plates, and she accepts.
The two end up having a great time, laughing together as Ralph walks Princess Carolyn back to her car. However, Princess Carolyn doesn’t know when she can see him again, due to her running her agency. Ralph still gives her his number, telling her to call him whenever she is available, and kisses her on the cheek before he leaves.
After Princess Carolyn closes VIM in It's You, she decides to call Ralph. When he picks up, he at first tells her a story, of how after their date he stumbled into a Russian ballerina and took her to the hospital and later married her. He quickly says he’s kidding, that he hasn’t stopped thinking about her since their date, and would love to go out with her again.
Ralph and Princess Carolyn are officially a couple by the next episode, That's Too Much, Man! BoJack stands outside Princess Carolyn's apartment building and shouts he's sorry. Princess Carolyn sighs, but is then accompanied by Ralph, who appears to be staying with her as he is in pajamas. The two smile at each other, and Ralph leads her back inside while looking over his shoulder and glaring at BoJack.
In That Went Well, Ralph and Princess Carolyn, who have recently been on a trip to Egypt, have dinner with Diane and Mr. Peanutbutter. There, he reveals he owns a greeting card company—but his family owns Stilton Hotels, which provides him with free residency when traveling, and makes him extremely rich. Princess Carolyn then tells Diane she should work for his sister, Stefani's, website GirlCroosh. He also supports Princess Carolyn, in wanting to become a manager instead of an agent, although he also points out a manager is practically the same thing.
In Season 4, Ralph and Princess Carolyn are still going strong. He asks Princess Carolyn to move in with him in See Mr. Peanutbutter Run, although she is hesitant and doesn't want to rush things. A little while later, when the two watch Mr. Peanutbutter and Woodchuck Coodchuck-Berkowitz's ski race, she apologizes for before and agrees to move in with him. She explains she turned him down before because earlier she found out she was pregnant, but before their date, she found out she miscarried. Ralph apologizes, telling her, to her delight, they should actually try to have a baby together.
However, a trip to the gynecologist in Commence Fracking reveals that Princess Carolyn has very little eggs left. He gives the two of them a fertility kit to help them get pregnant, including a watch that tells her when she's ovulating.
The iOvulate goes off while they're at lunch, and Princess Carolyn demands he drive them home, a makes up a story about their amazing potential son, Philbert, but he won't exist if he doesn't take them home immediately. Ralph tries to drive home as fast as he can, but they are pulled over by the police and are arrested. In the police car, Ralph confirms to Princess Carolyn he has really good lawyers, so the two have sex in the back seat of the police car.
Princess Carolyn is revealed to be pregnant in Stupid Piece of Sh*t.
Ralph takes Princess Carolyn to meet his family in The Judge at Stilton Acres for The Feast of St Squeaky, the holiest of all mouse holidays. He hopes his parents will like her, and Princess Carolyn assures him they will love her, and the two agree they'll wait until after they warm up to her to tell them she's pregnant. At Stilton Acres, Ralph's parents introduce themselves and the rest of the family. They offer her numerous things to Princess Carolyn you shouldn't eat/do when you're pregnant. Ralph is able to change the subject.
The Stilton family and Princess Carolyn have dinner for the Feast of St. Squeaky. Princess Carolyn expresses how much she's enjoyed her stay, and Ralph's father says they love having her. He announces, to let the festivities begin, and tells a relative to hand out the cat ears. As this happens, Ralph explains the feast is meant to remember the ancient tale of a brave mouse named St Squeaky and how he defeated the tyrannical cat King Puss Puss.
The family begins to sing a song about said cat king, saying how dumb, smelly, and evil cats are, and how St. Squeaky defeated him by stabbing him in the belly. Princess Carolyn whispers to Ralph that she wishes he told her the family was anti-cat, and Ralph tries to explain the song is just about one bad cat, not all cats. A relative shouts “Death to all cats!”. Princess Carolyn is of course offended by this and leaves.
Princess Carolyn is in bed, angry. Ralph enters, still wearing his cat ears. He takes them off and apologizes to Princess Carolyn. She questions why he didn't tell her his family hated cats, but he tries to deny this. She says she now knows why he wanted to wait to tell his family about the baby. Ralph confesses that he was a little nervous, but promised they'll come around. He then asks what he's supposed to do, because they're his family. Princess Carolyn asks what she and Philbert are, which makes Ralph feel guilty.
The next day, Princess Carolyn and Ralph leave Stilton Acres. The family says their goodbyes. After Princess Carolyn says goodbye to Ralph's parents and goes inside the car, they tell their son his girlfriend was “darling for a week” but maybe next time he'll bring home another girlfriend who can appreciate a St. Squeaky's feast. Ralph proclaims that he loves Princess Carolyn, and they're having a baby and he couldn't be happier. Princess Carolyn smiles from inside the car as she hears this.
However, in Ruthie, she has possibly one the worst day of her life; Courtney Portnoy fires her, she fires Judah after finding out he lied to her about a deal to merge with another agency, she miscarriage again and is told it is very unlikely she can get pregnant again, and her necklace, which she once thought was a priceless family heirloom, is fake, worthless costume jewelry.
She breaks down crying in her car until Ralph calls her. She assures him everything is okay, and he says she's so easy. At dinner, she doesn't tell him about the miscarriage, as he's really excited about the baby. However, she tells him she doesn't feel good and says she'll see him at home. She goes back to her old apartment, however, and drinks heavily with Todd and his clown dentists who had been living there. She makes all of them hide when Ralph shows up.
He is distraught she still has her old apartment and that she's drinking, but a drunk Princess Carolyn assures him it's okay because she miscarried. Ralph apologizes, but she quickly assures him it's okay and they just have to keep trying. Ralph isn't sure, as she's already had two miscarriages, but she actually reveals she's had five miscarriages throughout her life.
He questions why she never told him, and she says she didn't want him to pity her. She doesn't want to give up getting pregnant and tells him if he can't accept that he should leave. He calmly tells her he thinks they should looks for other options, so she breaks up with him and angrily tells him to get out of her apartment and find another "easy" girlfriend.
In Season 5, Mr. Peanutbutter comes to Princess Carolyn as the show, Philbert, ends its first season. He wants to turn a birthday card into a TV show and asks her to obtain the rights. She turns the card over to discover that it's made by Ralph's card company.
She meets with him for dinner. They both mention neither of them are seeing anyone and she mentions Philbert, which he is surprised about. She tells him it's the name of a TV show and not the baby they didn't have. Tracy calls her asking her to go to the hospital for a sudden adoption and Princess Carolyn freaks out. Ralph drives her to the hospital.
In the hospital, they sit in the waiting room. Princess Carolyn asks why he didn't call her after he left. He says that she seemed angry, so didn't think she wanted him to. She says she didn't, but he still should have called. He counters that she could have called him. She says that she wished he stayed with her even though she told him to get out and that the lesson is that he shouldn't listen to her.
Princess Carolyn holds the baby and Bridget, the birth mother, remarks that she's glad he's going to a good home with a mother and father. Before Princess Carolyn can correct her, Ralph agrees. Princess Carolyn and Ralph start arguing and she tells him he should leave, but he refuses, not wanting to make the same mistake he did last time. He insists she doesn't have to do it by herself, but she says she wants to because she loves the baby. That inspires Bridget to take back the baby because she realizes she can raise the baby on her own because she loves him and demands for her son back and tells Princess Carolyn she is inspirational.
Princess Carolyn takes the car seat out of the backseat of his car and refuses to be driven home by him. Ralph asks if they can wait for the cab together.
- Ralph appears to be very fond of cheese, as stereotypical mice are, eating at least two plates of it in That Went Well.
- Ralph's last name, Stilton, is a type of cheese.
- It is also a play on the Hilton Family, who own Hilton Hotels.
- It is also a reference to the book character, Geronimo Stilton.
- Ralph is homonyms with a popular 60's and 70's children's book character, Ralph S. Mouse, who was created by writer Beverly Clearly and popularized through a series of books starting with The Mouse and the Motorcycle.
- Ralph also bears great resemblance to a character named Geronimo Stilton, protagonist of a series of children's books by the same name which was written by Elisabetta Dami. They share the same last name, species, and dress similarly in a green coat and round glasses.