Heinrich first appeared in Operation: J.E.W.E.L.S., where he opens the hidden tomb of "King Two Tons-of-Candy" with a Blurpleberry Jewel stolen from Numbuh 5, and upon doing so turns into a giant candy monster. Due to not sharing any of the candy, however, it tastes like asparagus, and he tries to destroy Abigail for "sabotaging" the candy. Heinrich is returned to normal when Numbuh Five reclaims the candy jewel.
In Operation: R.A.B.B.I.T., Heinrich finds a volcano containing chocolate lava that turns anything that touches it to chocolate in the jungle within the jungle gym at Gallagher Elementary School and steals the first grade's pet rabbit, intending to turn it into a realchocolate bunny. Heinrich is thwarted by Numbuh 5 and Numbuh 2, as well as a girl by the name of Jessica, and ends up falling into the crater of the volcano to die. At the end of the episode, however, he is seen emerging from the volcano as a chocolate monster.
Heinrich returns in Operation: C.H.O.C.O.L.A.T.E., which directly continues this storyline, to enact his revenge on Numbuh 5. Everything he touched was turned into chocolate as well, which initially worked out well for him. After a time, however, Heinrich grew tired of chocolate and began craving a cheeseburger. When he tried to eat one, it turned into chocolate, and soon realized that he could not eat anything but chocolate and falls into despair because of his "Midas Touch" and vows for vengeance against Numbuh 5 by attacking her family and teammates in the time searching for her. Heinrich is defeated through Abigail's clever use of intense sunlight to turn him into fondue and then using "Marsmallows", marshmallows found on Mars, to completely liquefy the crazed candy hunter. Afterwards, his chocolate remains are taken to the KND Arctic Prison, where the Kids Next Door scientists resurrect him and remove the chocolate-based powers for good. While incarcerated, Heinrich receives a package from Numbuh 5 containing a cheeseburger, what he desired after all his time under the curse, and was brought nearly to tears as he began to eat it. Unfortunately, it has pickles on it, which he openly states that he hates above all else.
In Operation: L.I.C.O.R.I.C.E., Heinrich had been kidnapped from prison by Black John Licorice and his band of evil Licorice Pirates, who need a candy seed that Heinrich selfishly ate while he was traveling with Stickybeard as his cabin boy a while ago; the Pirates needing the seed in order to break a licorice-based curse that was bestowed on them for cutting down licorice trees. Numbuh 5 joins forces with Stickybeard and his Candy Pirates in order to track down Black John and rescue Heinrich. Together, Stickybeard and Abby succeed, and Heinrich is once again sent to Arctic Prison by Abigail.
In Operation: C.A.R.A.M.E.L., his final appearance, the incident in Guatemala 5 years ago is explained. In order to create pieces of ancient golden caramel, a magic ritual was performed that took away the most valued quality of the human in question and turned their most prized quality into five pieces of delicious caramel with flavor depending on the quality taken. Heinrich selfishly ate all of his caramels, causing him to lose the quality he sacrificed forever. Knowing that Heinrich could not control greed, Abigail left him behind, and Heinrich blamed her for becoming cursed.
Five years later, he tricks Abigail into a truce and uses the ritual to connect all the KND within half the continent of Central America and performs the same ritual using the massive amounts of candy contained inside them, affecting all the operatives in the treehouses. Heinrich taunts the now nerdy and pathetic Numbuh 5 while eating all her caramels, but before he eats her last one Numbuh 5 reveals that she has been keeping Heinrich's last piece of caramel from five years ago, and thus his last chance to break the curse: waiting for him to learn how to share. In a fit of blind fury Heinrich pushes her aside and takes the caramel, and tries to eat it for good, Abigail reminds him of how they used to be and how much she cares about him. Thus, Heinrich is driven to tears and gives her back the caramel, thus breaking her 5-year long curse and returning to normal again.
Everyone affected by the ritual is also returned to normal, and it is revealed that Heinrich is really a beautiful young girl named Henrietta Von Marzipan who is Abigail's best friend and former candy hunting partner. Their friendship is restored and they bid each other farewell, but the other members of Sector V are understandably confused by this revelation, but Numbuh 4 remains oblivious untill Numbuh 1 explains.
He/She played as Augustus Gloop in Stan Marsh and The Chocolate Factory
He/She will be the First Winner of the Golden Ticket, Who is from Germany, Who eats Candy and Chocolate, But He/She will be falling over into the Chocolate river.
He/She played as Anna Schmidt in Mind Your Language (RebeccaTheSorceress' Version)
He/She is a Student from Germany.
He/She played as Uter Zorker in The Simpsons (RebeccaTheSorceress' Version)
He/She will be the Foreign Exchange Student from Germany, Who loves Candy.