Unlike Boomer, he inherited his dad's skin color. He says he is older of the two, but no one knows. Brady is more serious of the two twins, and is normally the more intelligent and the braver, he is however less conifident in himself than Boomer.
Brady is also somewhat arrogant, as is Boomer, commonly believing himself capable of things he is unable to do, and at times is almost nassisist, commonly complimenting himself, and naming himself "King Brady, the all powerful and Adorable" Despite this, he is generally polite to everyone, and mostly friendly. He is, however, less trusting than his brother, as shown in "The Brady Hunch" and more unwilling to admit he's wrong, as shown in "Dinner for Squonks".
Again, much like Boomer, Brady is somewhat eccentric, enjoying and taking part in unusual activities, such as having his breakfast thrown at him, sleeping in a bed made of money, and a nest, and keeping dozens of cookies under his sheets. The best example is probably, when he was younger he spent years acting as harry potter, dressing up as him, and even refering to other people, as characters from the book.
Brady does however have something of a darker side to his personallity, possibly through years of being bullied, and being told what to do, he has no problems using or abusing his power, and can be quite harsh to anyone who questions or disobeys him, in "Big Kings on Campus" he causily threatened to send the teacher to the dungon for arguing against his proposed holi-month, in "Oh Brother, Where Arr Thou?" He was furious upon discovering Mason and Mikayla had lied to him, and considered sending them to the dungeon, something he only retracted when the agreed to do all the work. Perhaps the best example is "No Rhyme or Treason" where he outlaws poetry, and threatens anyone who breaks this with imprisonement, even using the palace guards to enforce his ruling.
He can also be rash, quick to anger, slothful, has bad hygene and prone to making bad discissions, at his worst, there are times when he has been almost cruel. Despite this, deep down he is a good person, and when duty calls he will stand to the occasion, several times he has risked his own life or safety for his brother, his friends and his kingdom.
Several times he performs acts of kindness, simply for that, for example he went to incredible lengths to try and reunite Mason with his brother in "How I Met Your Brother", another time he went to greater lengths, to his help his brother recover (after he thought he had lost his girlfriend) by domesticating a cave girl who fell for him, even going back repeatedly after literally being thrown out by her, and gave her a complete makeover. He also couldn't bring himself to take the peoples money, and thus started stealling the money back from his tax collecters, and giving it to the people, event though he was massively in debt, in "King of Thevies"
Brady is able to play the guatiar, and is a very good singer, something that apparantly runs in the family, and is known to the island as "the chime". He however didn't perform for years, as he didn't want to be better at something than Boomer, as shown in "Tone Deaf Jam"
Brady is more skilled at combat than Boomer, due to Mikayla's combat training, in 'Oh Brother, Where Arr Thou?' he took down a pirate using the pirate's peg leg (although he started the fight with a sword) without any help, he also took down several Tarantula people in "Prom Kings" and was able to match blows with Farhog the Firece for a few minutes in "Brady Battles Boo-mer," he also took down a few of Lanny's thungs, and beat them in a sword duel while posing as Sirocco in "King of Thevies" He also was able to match blows with Lucas, when fighting on his ship in "The Ex-Factor".
Despite rarely exercising, Brady is often shown to be highly agile and flexible, able to do somersaults, and even front flips with no apparant difficulty, he is also shown to be quite durable, recoving from injuries, such as been litterarly thrown out, and having a hundered pound tomato hit him, after a few minutes. He like Boomer is able to survive great falls, down to the fact that they took a class on surviving falls, back in Chicago. "Kings of Legend"
Brady also has the unusal habbit, that sometimes when he's asleep, he turns into "Sleep Ninja Brady", who acts exactly like a ninja, acording to Boomer, this habbit stems from Brady, watching Kung fu movies every night before he went to bed. While a ninja, Brady gains incredible skill in hand to hand combat, able to take down four guards and even Mason, however he has no control over this, and normally attacks Boomer. "Sleepless in the Castle"
He has a crush on Mikayla and wishes to one day marry her and make her his queen. He makes no effort to hide this crush, and always compliments/trys to flirt with her. However, he didn't gain the confidence to ask her out till "Good King Hunting"