I FLIPPIN' LOVE THE CRAP OUT OF NEJI, MAN.
H-HE'S JUST SO GREAT.
And, actually, I've had this obsession with his character since the very beginning of the Naruto franchise, but I always enjoyed seeing him together with Tenten, because I totally love NejiTen <3

BUT I LOVE NEJIARAI EVEN MORE UHUHUHUUUUU <333 Or as I so affectionately name their pairing: Nejai <3

OH. And, even though Arai has the eyes of a Hyuga, she has pupils due to her Takameshi clan. When using Byakugan, her pupils disappears and her Hyuga traits take full control. When not using Byakugan, her eyes return to the use of a Takameshi.

But yeah, a basic run-through of their ages, appearance, and relationship.

NARUTO
Neji Hyuga, 100% Hyuga boy, grown and raised within the Hyuga Manor. Arai Takameshi, holding blood from her father's Takameshi clan as well as her mother's Hyuga clan. They aren't cousins like Neji and Hinata, but holding the same last name and kekkei genkai, I'd suppose that they're linked, even if they're 32nd cousins or some shit, no? In this series, Neji doesn't really care much for Arai, but she is the only other person around his age who could try him at the gentle fist. Of course, she never won, but she put up a better fight - hand to hand, using the same technique - than anyone else. Her optimistically bubbly attitude usually pisses him off, but he gets used to it. She never goes away anyways. After the Chunin exams and after Sasuke leaves, Neji and Arai spend more training time together. He is much more tolerant of her and willingly knows a lot about her, from her fighting skills straight to what she could be thinking in her brain or in her heart.

NARUTO: Shippuden
Just a couple years older, these two grow into a great force to be reckoned with. Their teamwork has grown superbly and, without even speaking, they are able to tell what the other is thinking and what their next move may be. This becomes useful to Lady Tsunade when she sends them out for special missions together, branding Neji as a Jonin and Arai as a Special Chunin. Their skills and teamwork aren't the only things that grew during the years. Their relationship and feels have also blossomed... though Neji would never admit it. Arai tends to tease him much more freely now, possibly sensing Neji's feelings for her and knowing how she feels about him. Of course, their complicated relationship doesn't interfere with Neji's solid personality, and he still shuts her down when he feels he needs to. During the time of the Fourth Great War, Neji confesses his feelings for Arai and a lot of cute stuff and blah. Neji's death brutally scars Arai, as she considered using a Forbidden Jutsu to revive him - which would have likely taken her life as payment. Her eldest brother (Keisuke), however, takes that role upon his hands, sacrificing his sin-filled life to bring back someone who could make more change than he had. Though Arai tries to stop Keisuke, he sets a barrier and goes through with the jutsu, effectively closing the gap in Neji's chest as well as bringing his soul back into his body - reviving him.

NARUTO: After THE LAST
Neji Hyuga, back to his glory, stronger and wiser than ever, marries Arai as he turns 21. A year later, he is bestowed the title of Head of the Hyuga Clan (because Hinata intends to marry into another family - which, in my headcanon, is not the Uzumaki clan 8'D). A year after that, Neji and Arai welcome their newborn twins, Keiichi and Hiroshi into the family. Keiichi takes on a resemblance to Arai while Hiroshi takes a resemblance to Neji. This is the start of their soon to be large family.

This is a very brief thing of Nejai. They're so much more complicated then this, I need to take the time out to write evvvverryyyything xD Eventually u v u

Just to be clear, these are my Naruto headcanon pairing~ <3

NaruSaku
Sasu-
KibaHina
Shino-
ShikaIno
ChouKarui
NejiArai (Araiko is an OC)
RockTen
KakaShizu
IruAya
GaaYu (Yukari is an OC)