Sasuke Uchiha (Brother)
When Itachi was younger, he had a playful personality with his younger brother, Sasuke.
After his defection from Konohagakure, Itachi became an individual who has self control of his emotions. The only time Itachi shows any form of shock is when his opponents are prepared to engage him seriously, however, even then, he still maintains his composure. In the spin-off, Itachi is also given a comedic role. He is often depicted with a childish personality, as shown when he is seen arguing with Sasuke on who is more foolish and changing the channel to what he saw fit.
Itachi Uchiha, like most of his clansmen, has straight jet black hair and onyx eyes. His hair is over the shoulder in length and always seen in a low ponytail. His face is framed with centre-parted bangs that extended to his chin. Itachi usually sports a stern look in his eyes. When he was younger, his hair was much shorter and his casual clothes consisted of a black collared shirt. When on duty as a Konohagakure Anbu, he would wear the standard uniform complete with arm guards,and a flak jacket.
As a memeber of the Akatsuki, Itachi is shown wearing the standard cloak of the Akatsuki and a black body mesh with dark v-neck shirt underneath. He's usually seen with his left hand resting on an opening of his cloak around the chest area. He also wears a Konoha forehead protector with a horizontal line across the Konoha symbol to signifies his broken ties with the village. Other accessories that can be seen on Itachi are his necklace, which has three metal rings and dark nail polish.
According to the Naruto series, Itachi is said to be a ninja of prodigious talent. He is powerful enough to exterminate his entire clan with the exception of his little brother whose life he chose to spare.
Itachi awakened and mastered the Sharingan, which allows him to see chakra, copy jutsu and cast genjutsu.
Itachi awakened the Mangekyō Sharingan, the advanced form of the Sharingan. Its design is three spiralling curves around the pupil. With his left eye, he could use Tsukuyomi, a genjutsu that trapped opponents' minds in an illusory world for torture.
With the Mangekyō, Itachi could use Susanoo. When used, Itachi's Susanoo wields an ethereal sword with the ability to seal any person it pierced into its gourd—hilt, the Sword of Totsuka, along with a shield that is said to reflect any attack by changing its chakra nature to counterbalance an attack, the Yata Mirror.
Despite these new enhanced visual powers, Itachi suffers eyesight deterioration every time he constantly uses the Mangekyō Sharingan, eventually leading towards blindness.
Itachi and his partner Kisame Hoshigaki walk into a tea shop and asked for a table, unaware that his younger brother, Sasuke Uchiha was sitting next to him. Sasuke then asked him why he was here. Itachi answered saying that they were here to collect the restaurant's Chiffon Cake. Sasuke then reminds Itachi of the tragedy he committed long ago, but Itachi misunderstood this and thought it was because he broke his favorite toy robot back when they were younger. The two then started to battle by trading insults and playing video games. Itachi decides to get serious and activates his Mangekyō Sharingan. Noting that his eyes gives him blindness, Itachi mistakes a young girl for Sasuke. Jūgo then suggest a heat endurance test to settle their fight by placing them under a kotatsu. Itachi says that this victory will be his and uses Tsukuyomi on Sasuke, making him see a group of Sumo Wrestlers huddled around him to increase his heat temperature. Sasuke breaks the genjutsu by using his Sharingan and plans on ignoring the heat by watching television. Itachi however changes the channel and explains that since he is the older brother he should pick out the channel. Sasuke denies this and fights for the remote. As a result, the two pull out their strong attacks and destroys the inn in the process. Itachi says that Sasuke has gotten stronger and departs along with Kisame. He then appears next to Suigetsu, Jūgo, and Karin, asking them to look after Sasuke. Itachi also leaves a message for Sasuke saying that his friends are strange.
Itachi and Kisame are at a park preparing for the Akatsuki meeting. Itachi believes that the meeting was not to have a Flower Viewing Party but to discuss the future of the organization. However, Itachi was incorrect and the meeting was to have a Flower Viewing Party, much to Itachi's disappointment.