Bokuto Kōtarō is a third year at Fukurōdani while Akaashi Keiji is a second year. Both being in the volleyball club, Bokuto is the team captain with Akaashi as the vice captain and official setter. Despite not having a backstory (yet), it is canon that these two have a close friendship with each other. Their ship has the dynamic of one being loud, childish and flamboyant while the other reserved, witty, blunt and more mature.
An attribute between them that is very distinct from other Haikyū relationships is the incident of Bokuto's emo mode (also known as his dejected mode). This is when Bokuto gets depressed because something didn't go as he planned and he curls up in depression. Akaashi is the only one fully capable of tending to Bokuto's moods - which is mentioned to be over 37 in total, all of which Akaashi has memorized.Additionally, it is also canon (according to an official Haikyū shop in Japan) that Bokuto has smaller hands than Akaashi.
The roles between who is pining and which is oblivious is very versatile in fan works involving the pairing.
It's a very common AU in fics for them to be in college or post-graduation with jobs and with Kuroo Testurō and Kozume Kenma as their closest friends. Oftentimes, these four are shown to have a common past of playing volleyball together or against each other throughout high school and perhaps even being in the same team through the course of college. Past team members like those of Fukurōdani, Nekoma, Aoba Johsai, Karasuno and Shiratorizawa are peppered or integrated into their current lives as co-workers, friends, past partners and the like.