Hayner is impulsive and determined, and is always looking for a new adventure. He is bold to the point of recklessness, once even charging Axel unarmed. He gets bored easily during uneventful times, as demonstrated when he constantly pesters his friends to do something during their summer vacation.
Hayner is also easily angered/irked, as shown in the very first scene in Twilight Town when he tells Pence, Olette and Roxas about how everyone labeled them thieves for stealing photos. He thirsts for some kind of recognition, as he is even irked when Roxas defeats him in the semi-final round of the Struggle tournament, leaving Hayner in fourth place (Hayner is soon moved up to third place when Seifer withdraws from the match).
Hayner has brown eyes, light skin, dark eyebrows, and spiky, blond hair. He wears baggy, camouflage-print capris pants, a short, sleeveless, grey vest, and a black muscle shirt decorated with a white, crudely-drawn skull and crossbones. His shoes are the same camouflage pattern as his pants, but also sport white tips, grey soles, and each has two intersecting, black belts in place of laces. Hayner also wears a white necklace with a yellow "X" charm on it and a brown bracelet on his left wrist with several silver pins in it.
He is good friends with Pence and Olette, and his group has a rivalry with Seifer's gang.
In DiZ's Simulated Twilight Town, he was Roxas's best friend. His boredom caused him to suggest that the group take a trip to the beach (prompting DiZ and Riku to intervene, as no virtual beach existed). In the Struggle tournament, he faces Roxas in the first round and loses. Hayner (or at least the virtual Hayner) holds loyalty and promises highly, and seen through his jealousy when he sees Roxas with Seifer and his emphasis on the promise he and Roxas made to share the winnings of the tournament. His jealousy is short-lived, though, as Seifer withdraws from the tournament and Hayner is moved up to third place, allowing him to share the winnings with Roxas.
In the real Twilight Town he and his friends don't mention Roxas at all, but seem to recognize Sora slightly, because they had met Roxas in 358/2 Days. Initially, he is somewhat hostile towards Sora, presumably because he, Donald, and Goofy barged in on their usual hangout while exploring Twilight Town upon their release from stasis. Also, he initially refuses to talk to them because they were busy with other matters at the time. However, he warms up to them and goes to see the trio off at the train station.
Hayner, Pence, and Olette attempted to get into the Old Mansion when they discovered that there was an alternate Twilight Town, and they also wanted to search for Kairi, whom Hayner called "our friend too" - he was attacked by Dusks. However, he, being headstrong and street smart, along with his friends Pence and Olette, helped Sora and the gang find the way into the virtual Twilight Town. It was a tearful moment for the four of them. It had felt like they knew each other and were never going to see each other again.
Hayner is also a competent fighter and is seen facing off against his rival Seifer in the finals of the Struggle competition during the ending credits.
Hayner is first seen along with Pence and Olette fleeing a giant swarm of Heartless marauding through Twilight Town. After Sora rescues them, Hayner and his friends are reminded of their digital counterparts' friendship with Roxas, and agree to aid Sora for Roxas's sake. They later meet at the old mansion, where Pence works with Ienzo to get what information is still in the old computer terminal left behind by Ansem the Wise. Hayner and Olette, meanwhile, tend to their part-time job of spreading advertisements for the new bistro that Scrooge McDuck opened in Twilight Town.
Later on, Hayner and his friends see Ansem forcefully escorting Ansem the Wise to the Old Mansion. While, Olette sneaks around and leads Ansem the Wise to safety, Hayner and Pence distract the Seeker of Darkness. Hayner goes so far as to attack Ansem and attempts to hit him with a flying kick. When the attack fails, he's rescued by Nobodies controlled by a traitor among the New Organization XIII, and makes his escape. Later, Ansem the Wise tells him, as well as Pence and Olette, all about their friend Roxas.
At the end of the game, Hayner, Pence, and Olette join Roxas, as well as their other new friends Lea, Isa, and Xion for a gathering at the clock tower to eat sea-salt ice cream. They later attend a larger gathering of friends at the Destiny Islands.
Hayner is a very offensive fighter. He isn't very good at counter-attacking or parrying and he tends to leave himself open after using his own attacks. Hayner will attack with a downward swing, a jumping uppercut, a stabbing attack, and a wide-arc swing. He doesn't seem to be very coordinated but can pack a lot of power.
- During the final visit to Twilight Town, Hayner tells Sora that "those white things" (meaning Nobodies) attacked him. However, the Journal says that Hayner and the others were attacked by Heartless.