Irving Du Bois

Irving is is Phineas and Ferb's self-proclaimed biggest fan.

Present life
He always carries a scrapbook that he filled with images and souvenirs from Phineas and Ferb's Big Ideas with him (such as the roller coaster, the chariot race, and the boys with some sort of soup, most likely from the time they created Chez Platypus). He has pictures and stories of the gang ever since day one. He even has a lock of Ferb's hair. He apparently was with them the whole day but had gone unnoticed because his horoscope says he's "the background type". He says he often has to digitally insert himself in pictures of their adventures to make it seem as though he was there as well. He is under the impression that Phineas and Ferb always have a plan, but is disappointed to find out that they have just been improvising the whole time ("Hide and Seek").

He also appears with Phineas and Ferb's group of friends in some occasions. When Doofenshmirtz's inator lands in Phineas and Ferb's backyard, Phineas addresses him separately ("Friends, bullies, Irving."), indicating that Phineas and Ferb don't consider him a friend yet. ("What Do It Do?") However, when Phineas and Ferb build the world's tallest building, Phineas is glad that Irving is present to help and openly invites him. ("The Doof Side of the Moon")

When they discover Atlantis, he mentions having gotten in the car when Linda stopped for gas, indicating that he wasn't invited onto the beach trip but blended in with the group. Buford and Baljeet do not seem to paticularly like him, calling him a nerd among other things ("Atlantis").

Irving also helps "Tri-State Area Unification Day" parade ("Hip Hip Parade"). When Candace teams up with Albert, he removes the cameras that Albert and Candace put up and tries to convince Albert to stop helping Candace ("The Doof Side of the Moon").

During the Sci-Fi and Fantasy Convention, he is involved in a battle between fans of Space Adventure (Speckies) and fans of Stumbleberry Finkbat (Finkies). He and Albert get in a fight because of their different tastes in genre. However, they are soon reunited when being forced to fight a strange monster, which is computer-generated, unbeknownst to them. ("Nerds of a Feather")

Irving was among the many people who sang in the number Summer Belongs to You, though his voice is never heard. ("Phineas and Ferb Summer Belongs to You!") During Phineas' birthday he suggested to make a clip show for Phineas using the clips he recorded ("Phineas' Birthday Clip-O-Rama!).

When Phineas and Ferb built a fun house, Irving was hit with Dr. Doofenshmirtz's "Least-Likely-inator". He then began saying that Phineas and Ferb were lame and started flirting with Isabella. This means he has little to no romantic interest in Isabella since he was doing the least likely thing he could do ("Misperceived Monotreme"). For Christmas, Irving receives Phineas and Ferb's trademark clothes and cuddles them dearly. ("Phineas and Ferb Christmas Vacation!")

Personality
Irving displays a characteristic obsession in Phineas and Ferb along with what they do. At the times he has the opportunity to participate in what they're doing, he's always excited to do so. However, he is often unnoticed because he is a "background type" person, as said by his horoscope. Like his brother, he'd openly flirt with anyone he feels love towards. ("Moon Farm")

Physical Appearance
Irving stands at around the same height as Phineas, but his body is larger by width. He has has buzzcut orange hair over a pair of dark blue eyes. Over his eyes is a pair of large glasses with a thick pink frame.

He wears a dark blue spory shirt with a white collar along with a pair or grey shorts. On his feet is a pair of sneakers which he wears above a pair of rolled-down black socks.

Albert
As his older brother, Albert is often shown harrasing or sometimes just being mean to Irving, doing things such as confiscating his collection of spy cameras and making him carry his Stumbleberry Finkbat action figures. They'd often dispute over their film genre preferences and rarely agree with each other. ("Nerds of a Feather")

Phineas Flynn
As mentioned above, Irving is Phineas's self-proclaimed biggest fan. He devotes most of his life to stalking and spying on Phineas along with his stepbrother Ferb. Although Phineas would often have him assist them in one of their Big Ideas, he doesn't appear comfortable with calling Irving a friend.

Ferb Fletcher
Their direct relationship is unknown, but Irving appears as obsessed in him as he is in Phineas. He has somehow obtained a sample  of Ferb's hair, as he has mentioned having one  in his scrapbook. He has also advocated to consider putting a picture of Ferb in his wallet. ("Hide and Seek", "Atlantis")

Candace Flynn
Irving is aware she is trying to get Phineas and Ferb in trouble and doesn't support it. ("The Doof Side of the Moon") However, he, like Albert has shown love interest in her. ("Moon Farm")

Background Information

 * Irving's physical appearance is based off of a boy seen in the episode "Raging Bully". Dan or Swampy have said that when it came time to design Irving, they selected that character model, but that boy is a separate person from Irving.
 * "Nerds of a Feather" reveals that he's a fan of Space Adventure.
 * His room is shown with its walls full of Phineas and Ferb pictures as seen in "Not Phineas and Ferb". The episode also reveals that he has planted motion sensors in Phineas and Ferb's room.
 * Irving is one of the few of Phineas and Ferb's group of friends who knows that Candace wants to bust Phineas and Ferb.
 * It is revealed in "Phineas' Birthday Clip-O-Rama!" that Irving records every single thing Phineas and Ferb do over the summer, including things that never happened on screen or were wiped out of existence or memory. (e.g. Everything that ever happened in any episode from the episode's point of view).
 * As obsessive as he is about Phineas and Ferb, he also seems to carry obsessions with other things apart from Phineas and Ferb, such as the film series Space Adventure ("Nerds of a Feather") and photography. ("Hip Hip Parade", "Atlantis")
 * He seems to have a crush on Candace and/or Stacy in "Moon Farm". His brother Albert has also hinted at romantic feelings in Candace in "The Doof Side of the Moon".
 * He can play the French Horn. ("A Phineas and Ferb Family Christmas")

Appearances

 * "Hide and Seek" (First appearencre)
 * "Phineas and Ferb Musical Cliptastic Countdown" (Speaking cameo)
 * "What Do It Do?"
 * "Atlantis"
 * "Phineas and Ferb Christmas Vacation!" (Cameo)
 * "Hip Hip Parade" (Speaking cameo)
 * "Not Phineas and Ferb"
 * "The Doof Side of the Moon"
 * "Phineas and Ferb Summer Belongs to You!" (Cameo)
 * "Nerds of a Feather"
 * "Rollercoaster: The Musical!" (Cameo)
 * "Phineas' Birthday Clip-O-Rama!"
 * "Moon Farm"
 * "Misperceived Monotreme"
 * "Phineas and Ferb The Movie: Across the 2nd Dimension"
 * "My Fair Goalie"
 * "The Curse of Candace"
 * "Ferb Latin" (Cameo)
 * "A Phineas and Ferb Family Christmas"