|U.S. air date:|| TV: August 27, 2015|
VOD: August 21, 2015
|U.K. air date:||October 13, 2015|
|International premieres:|| Germany: October 23, 2015|
Bulgaria: October 23, 2015
Australia: November 6, 2015
Spain: November 14, 2015
|Written by:|| Ben Bocquelet|
|Storyboarded by:|| Wandrille Maunoury|
"The Signature" is the fifth episode of Season 4 of The Amazing World of Gumball.  It is the 121st episode overall.
In the Watterson's house, Richard is using tools to hang a picture of the Watterson's vacation outside the bathroom, unaware that his actions ended up demolishing said bathroom. Louie who is with him commented about how great that vacation was, but Richard ended up with sunburn which he peels off and eats. Louie told him to watch his diet and Richard replies that no one ever told him these things and wished to call Louie father. Despite the awkwardness, Louie delivers the big news, that he and Jojo are getting married. Richard was stunned by the news and grinds his teeth to hold back his outrage, saying he was alright with it. Louie was impressed since he was expecting him to explode. That happened later when Richard's grinding teeth ignited the gas leak in the bathroom, triggering the explosion and sending Louie flying outside. He dusted himself and went back inside with Jojo who asked how'd it go. The kids went up to see Richard who is still stunned and figured that Louie told him the news. Richard declares that he won't let Louie take away his mother but Darwin tries to reason with Richard to adopt a positive attitude for Louie. Richard then began to have thoughts on what Darwin said and Gumball, fearing what their dad might do intervenes and tells him not to adopt Louie so that he could forbid the marriage, but Richard was thinking of something else and decides to go along with Gumball's idea.
At the table, the family are preparing the wedding invites while Richard strolls in asking about the guest list for the wedding and quietly places adoption papers on top before asking Louie to add his name onto the guest list. The kids were wondering what's he doing and Anais points out the adoption papers that Louie is unwittingly signing while Richard was grinning like a shark. They tried to warn him but it was too late, the signature was done and Richard rips off his shirt gloating that Louie is his son now and cancels the wedding. The family were shocked at what he's done but Richard told Louie to go to bed and he complies as he was raised to listen to his parents.
Louie is now forced to bunk in Gumball's bed and Gumball tries to cheer him up, but accidently gave Louie an idea to get back on Richard. He went to Nicole and tricked her into signing adoption papers making her his daughter and deny Richard from seeing her. The family are inside while Anais describes to them the situation since they are confused at these changes in the family positions while Richard has a bag over his head since he is not allowed to see his wife. Darwin, in a moment of clarity concluded that Granny Jojo is the most powerful member of the family but Anais points out that she is technically their half sister in law and that her ex husband Frankie Watterson is the holder of that title. She was furious at the mention of that man and quarrels with the adults who then began to brawl. The kids then decided to contact the missing family patriarch to legally adopt Richard so that this mess is straightend out.
In an old apartment, Frankie is eating cereal and complains as the repo-men are taking away his possessions due to his overdue rent. As he read the paper for a job, he sees the ad placed by the kids asking him to come home. In his head, he believed that he has found a chance to get a free home. He later arrives at the Watterson home and meets the kids who reunite him with Richard. Richard initially ran to him in joy, then shake him in anger for coming back without milk and then breaks down in tears. The kids explains that Frankie is here to adopt their dad to fix this mess. Frankie then asks his son to sign the papers for adoption. Richard was overjoyed to have a complete family again but turns around to see his dad gone with pieces of his shirt on the ground. Jojo looked at the papers and discovered that Frankie tricked them into giving away the house to him. They collapsed in shock but Anais realise that if Louie marries Jojo and takes her name, he will become the most powerful man in the family and they can get their house back. With no time to lose, they drive toward Elmore City Hall to get that marriage licence.
After crashing in front of city hall, the Wattersons reached the receptionist who told them that they will have to take the line for those who don't know what line they need to go. Over there they see Frankie waiting in line and after exchanging words, Gumball slows him down by knocking him down while Nicole "persuades" the clerk to do his job. Their mad dash for a marriage licence take a pause as they were literally caught in a maze of red tape and Frankie barred the exit, preventing them from stopping him. He regrets doing this but after seeing the sadness in his son's eyes he remembers the night he first left a young Richard who waved goodbye at him believing he was getting milk. He was broken out of his flashback as the clerk asked him if he is in line, but Frankie replied that he was out of line for too long. He removes the red tape blocking the Wattersons apologising for his actions and they learn he is having a moment of humanity, which they took advantage of and got the marriage licence stamped, making Louie and Jojo officially married. The Wattersons celebrated their victory but Richard sees his dad walking away and stops him for a minute, asking him to sign these papers first. Frankie believed they were restraining orders but Richard said they were to make him his dad again since he missed him so much. They happily reconcile as they rip their shirts off and sing about being family along with the rest of the Wattersons.
- Richard (Semi-Antagonist until the end)
- Granny Jojo
- Frankie (Antagonist until the end)
- Marvin Finklehimer
- Doughnut Sheriff
- Paper Woman
- Siciliana Pepperoni
- Hexagon Lady
- Gary Hedges
- Harold Wilson
- Principal Brown
- Mr. Small
- Cupcake Woman and Man (debut)
- This episode was released on the Cartoon Network App and Video on Demand before it aired on TV, along with "The Egg," "The Crew," "The Others," and "The Gift."
- This is Louie's third major role in an episode. The first two were in "The Extras" and "The Man."
- Animation from "The Authority" is reused.
- This is the 3rd episode that includes a sign of Frankie Watterson. The first two were in "The Watch" and "The Man."
- Nicole attacks Granny Jojo in the same way she did in "The Authority."
- One of the pictures that Richard replaces his family with is a picture of the woman from a commercial in "The Downer."
- Gumball makes his evil face from "The Move" again.
- In one scene, Anais' eyes are ovals, the first time since Season 2.
- The same happens with Richard near the end of the episode, the first time since "The Joy".
- A Xenomorph-like inner jaw emerges out of Nicole's mouth when she threatens the Cupcake Man.
- The song the Wattersons sing when celebrating themselves as a family is a parody of the song "We Are Family" by Sister Sledge.
Richard states that Frankie has been gone for 33 years, contradicting his previous statement of 42 years in "The Man."