|“||Hey Ferb. I know what were gonna do today.||„|
|~ Phineas Flynn's catchphrase.|
The most notable trait of Phineas is his enduring optimism, along with his ever-cheerful demeanor he always strives to uphold. Even in the face of the most difficult challenges that confront him, he manages to maintain his composure and keep his outlook on the situation positive. Phineas often uses his ability to boost the morale of those around him during phases of depression. He is almost always in a good cheerful mood.
As intelligent and industrious as he is, however, Phineas has shown to be oblivious to the emotions and intentions of those around him. It's for this shortcoming of his that he fails to notice Isabella's love interest for him as obvious as she tries to make it, along with Candace's intention to get him grounded. It is possible that Phineas inherited this shortcoming from his mother considering how she always ignores Candace's often completely justifiable rants of the impossible endeavors he and Ferb would engage in and how she has always neglected to acknowledge the frustration Candace would feel when she on one occasion found herself in her daughter's position. ("What Do It Do?")
Being a rational and calm person, Phineas isn't easily angered or irked. However, he has been shown to be innovative to a fault; when Phineas is unable to express his creativity he may build up high amounts of stress. ("Bully Bromance Breakup"). On very rare occasions, Phineas's temper has been flared. The first traces of Phineas's aggravated side were seen when Candace ignored his warnings and put herself in danger ("Out to Launch") and when Baljeet's distraught wailing interrupted his morning ("The Baljeatles"). Phineas also openly showed his intolerance when Santa dismissed the entire population of his hometown as "naughty" ("Phineas and Ferb Christmas Vacation!"). He was agitated to a particularly high extent when on what came close to turning out as a pivotal event in his family's history when he finally learned of his pet platypus Perry's secret double-life as a secret agent. (Phineas and Ferb The Movie: Across the 2nd Dimension)
Though a handful of instances Phineas has openly shown exasperation can be listed, there has only been one time Phineas was well and truly enraged. That time was on the day of the Summer Solstice, when Candace refused to cooperate with him during a critical moment when he needed for her to swallow her pride and settle for the tricycle that was the only means of transportation available for her to make it back to their house. Under the circumstances of a dwindling time frame, Phineas eventually resorted to yelling at her in a startling outburst of rage to force her to comply. ("Phineas and Ferb Summer Belongs to You!")
Phineas has short, spiky deep red hair, a triangle shaped head with a large pointy nose, and large, dark blue eyes. He has three freckles near his temple. His height is not revealed yet, but he seems to be slightly shorter than Isabella and taller than Baljeet. Phineas also has a slight but noticeable slouch. It is uncertain whether this is a medical condition (possibly pertaining to the size of his head), or formed of simple habit.
As a toddler, Phineas wore a white t-shirt, blue overalls and black shoes.
Currently, Phineas wears an orange and off-white striped t-shirt, blue cargo shorts with large pockets, and blue high-top sneakers with no noticeable socks. He also wore this outfit as a toddler and preschooler.
Phineas's swimsuit consists of an orange pair of swimming trunks with a white cloud pattern, with dark blue sandals to match.
For winter, he wears a dark blue jacket over a white turtleneck sweater, dark grey snow pants, grey gloves, and a red snow hat in the snow. He has grey boots with this outfit ("Phineas and Ferb Christmas Vacation!"); he wears a light blue turtleneck sweater with a snowman on the front in place of his regular ("A Phineas and Ferb Family Christmas"). His indoor winter clothes are a variant of his summer clothes; a long-sleeved orange and off-white striped shirt, and blue cargo pants. ("Happy New Year!")
For bedtime, his PJ's are striped orange with a white neckline and cuffs ("Brain Drain") and later on is orange with white stripes with an off-white turnover collar with buttons.
In "Act Your Age", as a tween, Phineas' hair was slicked back instead of spiky, and wears a gold buttoned shirt, slate blue cargo shorts, and bluish-grey sneakers with white laces.
Also in "Act Your Age", as a young adult, Phineas' head is nearly the same as when he was younger, but with his hair slightly longer and returned to its usual spiky hairstyle. His height still remains unclear, but he seems to be a whole head shorter than Ferb and a bit taller than Isabella.He now wears a gold T-shirt with an orange stripe layered over an off-white long sleeved shirt, jeans, and dark blue sneakers similar to the ones wore as a kid.
Phineas has proven himself to possess numerous talents and skills. Like his brother, he possesses an overactive imagination that is the driving force behind his endeavors. He can work very well with tools and has exceptional knowledge and prowess with construction. What distinguishes him from others of his age group is his ability to engage in feats largely amplifying that of others his age.
He also has been shown to be a good singer. When given the opportunity to sing, he seizes it and delivers with remarkable vocal proficiency and smoothness. Along with this, he can play a number of musical instruments, including and possibly not limited to the stand-up bass, the guitar, the bass guitar, the organ, the piano, the tambourine, and the drums.
Phineas appears to be able to work very well as an investigator, having been able to track down and locate Candace's Mary McGuffin doll based on eyewitness testimony after it was mistakenly sold in their garage sale. ("Finding Mary McGuffin")