Rin didn't know how he got together with Isagi. He remembers arguments, remembers disregarding that damn NPC's tries to get closer to him, remembers saying he will kill Isagi and devour him and make him despair.

So how did it get to this?

4 years after Blue Lock, a 20 years old Rin lay on Isagi's bed in Isagi's apartment, inhaling the strong scent of the blue-eyed striker's cologne in Isagi's old Bastard Munchen uniform like a dying man. He buries his face on the fabric, groaning as he breathes Isagi's scent in and out.