The Delightful Children From Down The Lane are the conceited secondary antagonists of the series bent on the destruction of the Kids Next Door Organization and the supremacy of adults over children. The DCFDTL speak in synchronization and stand together in group formation. Their names are Bruce which is the short blond boy, David which is the tall brunette boy, Lenny which is the boy in the helmet, Constance which is the short dark brown haired girl, and an unnamed blond girl has a pink bow. Although the Delightful Children answer to Father, they are seen acting independently just as often. The Delightful Children rarely partake in direct combat, usually sending other villains to do their work and controlling combat machines. Although the secondary antagonists of the show, they make more appearances in the series than any other villain, and more than any character other than the five members of Sector V. They are obsessed with behaving properly and wish to become adults as soon as possible.
All five children have icy, light blue eyes. They wear school uniforms; the three boys are wearing blue uniforms with gray badges, red ties and brown shoes, and the two girls wear white sailor-like dresses with sky blue stripes and matching scarfs with white shoes and pink socks.
- Bruce has blond hair.
- Lenny wears a red helmet with a white stripe in the middle.
- David is tall and has brunette hair that covers his eyes.
- Unnamed girl has long blond hair and wears a pink bow.
- Constance has dark brown pigtail-braided hair tied in a red hair-tie, and wears glasses.
The Delightful Children from Down the Lane are creepy, but nevertheless delightful. They were more cool-minded in the first few seasons, unless their plans were thwarted by the Kids Next Door. In later seasons, they show more emotion such as irritation and become more determined to destroy their enemies.
They acknowledge that they are 5 separate people with individual names (as proved in Operation: U.N.D.E.R.C.O.V.E.R.), and can act individually. When startled, the Delightful Children become disoriented and briefly cease their synchronization with each other.
The Delightful Children celebrate their birthday five times a year, as they are technically five people. They prepare a delicious cake they intend to eat without sharing with any other kids and force their guests to watch as they do so. Sector V personally attempts to stop them from eating their cake at all costs whenever they celebrate their birthday, which occurs six times throughout the series and composes a recurring storyline, throughout which this simplistic scenario is repeated with several variations and exaggerated to absurd lengths. In each of these episodes, the cake is stolen, destroyed or in some way rendered inedible for the Delightful Children, save for Operation: S.I.X., where Numbuh 2 is tricked into personally delivering their cake to them. This leads to Numbuh 362 giving the mission to Sector W in Operation: I.N.T.E.R.V.I.E.W.S..
The Delightful Children have almost never worked together with Sector V. However, in Operation: Z.O.O., they and Sector V had to work together to escape their zoo enclosures (which they were not on board with at first), only to later reveal their entrapment was part of a set-up to destroy Sector V.
In Operation: P.A.R.T.Y. they call Sector V to help them get the Teenagers out of their mansion before Father returns home. At first, Numbuh 1 doesn't care about this situation, but the Delightful Children remind him that it's the KND's job to help kids no matter what the consequences are, to which Numbuhs 2-5 agree with the Delightful Children. Numbuh 1 does agree eventually, but still doesn't trust them.
In Operation: U.N.D.E.R.C.O.V.E.R., Lenny, the child with the helmet, is apparently revealed to be an undercover KND operative and leaves the DCFDTL to assist the team during their attack on the coffee rig, during which time he functions independently and acts like a normal kid. However, this is revealed to be a ruse, and Lenny returns to the Delightful Children towards the end of the episode. Even after this is revealed, Lenny alone is responsible for the error that causes the Delightful Children's defeat, for which the other four call him an idiot, which could mean he might be still against their plans.
In Operation: F.O.U.N.T.A.I.N., it was revealed that the Delightful Children were responsible for making Numbuh 1 bald, which was done in such a way that his hair would never grow back. This occurred shortly before he joined the KND, and is never shown and only briefly mentioned, leaving the circumstances of the incident up to the imagination of the viewer. At that same episode, they kidnap Leaky Leona and attempt to destroy the Fountain of Youth in order to prevent anyone from remaining a kid, but they failed.
One of the worst things that the Delightful Children has done was in Operation: B.U.T.T. when they were going to put a picture of Numbuh 1's butt in the school yearbook to attempt to make him quit his team, with thousands of Robot Crabs taking a picture of his butt. The plan was foiled by the rest of Sector V, and are left embarrassed and run away from the Robot Crabs.
In Operation: E.L.E.C.T.I.O.N.S., they make a deal with Chad to let the students of his middle school enslave the students of Gallagher Elementary in exchange for being "promoted" to middle school level, thereby becoming "that much closer to glorious adulthood."
In Operation: C.A.K.E.D.F.I.V.E., Father creates an ice cream cake for his children and attempts to destroy all other ice cream, planning to have all the children in the world watch as they eat the last ice cream in existence. Father's plan failed, and the delightfuls are covered by the cake itself upon crash landed.
In Operation: I.T., the Delightful Children betray Father in order to stop his plan to spread broccoli throughout the world to force feed to children, which even they are against, because they are still children, and even they hate broccoli, so they help Numbuh 1 and Numbuh 362 to stop Father.
In Operation: Z.E.R.O., after the revelation of Sector Z, the Delightful Children are re-commissioned by the re-commissioning Module, restoring them to their former selves as KND operatives; Numbuhs 0.1, 0.2, 0.3, 0.4 and 0.5. However, the effects of delightfulization were so powerful that any reversion is temporary, and the re-commissioning module's effects wear off during the final battle on the moon base. Sector Z's final words to Numbuh 1 as the delightfulization takes hold again are "Tell... the Kids Next Door... that we miss them!" Now, back to their delightfulized selves, they pummel Numbuh 1. But Nigel defeats them, and sending them to space in a escape pod.
The last we see of the Delightful Children is in Operation: I.N.T.E.R.V.I.E.W.S., where they celebrate their birthday. Sector V attempts to chase them, but the delightfuls escape. Then, both Sector V and the DCFDTL clash again in Sector V's Treehouse, alongside Father, for filming a movie of the delightfuls eating the cake, much to Sector V's dismay.
To their horror, however, Numbuh 74.239 appears instead of the cake. Later on, the children talk to Father about the scavenger hunt in their mansion, and decide to participate to retrieve their cake. They actually get ahead of themselves, as they presume to cheat the competition. When Numbuh 1 returns to the amusement park with Father's pipe, the children furiously begin to battle him for it, and end up on a log-river ride. They get him into a hold by using Numbuh 1's S.P.L.A.N.K.E.R., and are about to end him once and for all, when Nigel grabs onto a sign as his foot knocks the pipe from their hands, while the Delightful Children fall into a broken part of the ride, and into a deep hole below.
- The blond girl's name has yet to be revealed.
- Constance is the only one of the five who has never spoken individually, even during their temporary reprive of the Delightfulization. *It is unknown if Numbuh 1 told the rest of the KND operatives that the DCFDTL was the missing Sector Z or not or if they ever found a way to recomission Sector Z during or after the series.
- In Operation: U.N.D.E.R.C.O.V.E.R., at the beginning of the episode, the Delightful Children captured Numbuh 1 and his teammates and chained them to an iceberg and were about to use a vehicle with giant hammers to smash the iceberg into smithereens to kill Sector V. Lenny though, accidentally flips the wrong switch causing to the Delightful Children's vehicle to go flying upwards saving Sector V.
- In Operation: U.N.D.E.R.C.O.V.E.R. Lenny's Brace/Helmet can morph on his face.
- The DCFDTL were the first characters apart from Lizzie or Sector V to have called Numbuh One "Nigie". They called him that in Operation: D.A.T.E. and later in Operation: F.E.R.A.L..
- If "Delightful Children From Down The Lane" is typed into the GKND website, the response is "Classified".
SuPer Educated Guesses Unfortunately Lack Actual Surety However Is Included On Notes
- Because they don't speak in unison when frightened or nervous, its reasonable to assume that the Delightfulization weakens slightly when their individual emotions surface.
- No explanation is ever given as to why Lenny wears a helmet. However, in Operation: U.N.D.E.R.C.O.V.E.R. Lenny is shown to be wearing a mouth brace beneath his helmet, and he may wear his helmet to keep it from getting damaged.
- Although they are supposed to obey all adults (notably Father), they were shown to disobey his orders when he was in a depressed state, implying that they refuse to obey an adult if they are considered weak. It's also possible that the Delightfuliazation process does not cause the children to become as delightful as Father thought.
- Also, despite apparently fearing Father, they have been shown to physically overpower him when he seemingly turns on them, as they did in Operation: Z.E.R.O.
- Because Sector Z has been considered lost for many years now, and the Delightful Children never seem to age, it is reasonable to assume that they may have achieved life-long youth, through their unique Delightfulization. This is rather ironic, considering that the Delightful Children's main ambition is to grow up.
- However, since they are 5 people and there are 7 C.A.K.E.D episodes, it is possible they did it 5 times the first year, and the rest of the C.A.K.E.D saga could be their last 2 birthdays of one of the Delightful Children. Based on that, it is possible they were actually delightfulized when them and current operatives were roughly a year younger than they are now.