It takes Irie several seconds to realize it's his phone ringing. The beeping is unmistakable, the sound of a cell phone identifiable without any other information, but he still looks around, convinced for a moment the sound is from his sister's phone, left somewhere in his room for an unknown reason. He is actually getting up, ready to go in search of the forgotten item, when he realizes the sound is from his pocket, that it is in fact his phone offering the insistent noise of the default ringtone.
He stares at it for a moment even after he has the phone out of his pocket and ringing in his hand. He doesn't recognize the number - no surprise, since he can count the number of calls he has received in this lifetime on one hand. It's more for emergencies than anything else, and even then more to comfort his own paranoid anxiety than for the sake of his mother. Usually he entirely forgets he has it; he can't imagine how anyone could have found the number. It keeps beeping, though, proof that someone does sounding loud in the air, and finally Irie flips it open and lifts the phone to his ear.
"Hello?" He sounds lost, the confusion creasing his forehead and settling sour in his stomach audible in his voice. He'd feel bad about sounding so clearly on-edge if he had the least suspicion who his mystery caller could be.
"Sho-chan!"
The voice comes instantly, like the person on the other end of the line didn't hear any of the confusion in Irie's tone at all. There's only the one word, the affectionate name chirping loud against Irie's ear, but Irie doesn't need any more than that to identify that voice, even if he's never heard it in anything but memory. His stomach twists, knots instantly with a bizarre combination of panic and delight and terror, pushed-aside recollections rushing over him too fast, like trying to live ten years' worth of events in the span of a heartbeat. Relief comes first, breathless joy that Byakuran is alive in this timeline, after all, the way Irie has always half-desperately hoped he was. Then there's the horror, panic swamping him and clenching tight in his chest as Irie remembers what he did, or what his other self did, betrayal not lessened by Byakuran's reciprocation, the plan to save the world that always felt like murder in Irie's head. And then fear, that Byakuran will remember, because if Irie remembers than Byakuran must too, Byakuran will come for him to get revenge for the world that never existed.
"Byakuran?" Irie hears himself say, his voice cracking high with the adrenaline drowning out his rational sense.
"Of course," Byakuran says. His voice is purring across the line, all the resonant tone that Irie loved, has loved, will love, the sound plugging into emotional responses too deep-seated for the reality of this timeline to overthrow them. "Are you surprised?"
Irie takes a breath. He feels like he's drowning, like his lungs are starving for the air all around him he can't manage to inhale. "You're not dead."
"Nope!" A laugh, bright and sparkling and wholly sincere as far as Irie can tell.
"Are you-" Irie's throat spasms, turns his words into a whimper as panic rushes ice-cold into every inch of his body. "Are you mad?"
"Mad?" Byakuran sounds delighted, amusement purring under his words even though he's not actually laughing. "Why would I be mad, Sho-chan?"
"I." Irie has never tried to put words to it before. He's spent the last months doing his best to forget the memories, at least when he's awake; at night they come for him, sweet dreams and nightmares alike, but he avoids the awareness as much as possible when he can. It makes it harder, now, to find the coherency to frame what it is he is trying to say. "I betrayed you."
"Not really," Byakuran says. "I knew you were going to. Really I betrayed you."
"I worked with your enemies," Irie says. He can feel the grief rising in him, the weight of years of dead-end-future knowledge finally coming around to catch him, has to force his tongue to work over the words instead of going still and cold in his mouth. "I got you killed."
"That's all in the past," Byakuran says easily. Irie can imagine the flippant motion of his hand, brushing aside this protest like it's so much dust in the air. "It didn't really happen."
"But." Irie's chest is aching, the pain rising like so much weight crushing him. "But I remember it."
"Me too." Byakuran is smiling, Irie can hear the expression lacing into his voice like syrup. "I remember all of it. That's why I found you. Aren't you impressed? It was hard to find this number, you know."
"Why?" That's a wail, almost a shriek that Irie can't modulate into something calmer. "Why did you want to talk to me? Still, after everything?"
"Sho-chan." Gentle, that, slow and condescendingly affectionate. "Of course I want to talk to you. You're my best friend, aren't you?"
The tension in Irie's chest relaxes, all the strain of painful adrenaline going slack all at once. He opens his mouth to say something - thanks, or gratitude, or much-delayed surprise - and the relief drowns him, claws its way up his throat as a shattered, broken sob. His eyes are blurring, burning hot with the force of years' worth of unshed tears, his hand shaking so badly he can't even get his hand up to cover the hysterical choking gasps that come spilling out of his throat.
"Sho-chan," Byakuran purrs, and Irie slides sideways to the floor, clutching his phone to his ear like the sound of Byakuran's laughter is the only thing left in the world. He can't breathe, he can't manage more than half an inhale between the shuddering, awful sobs that are shaking him against the floor, and there's no space for speech in the rush of unbearable gratitude that is drowning him. Byakuran is talking again - Irie catches disjointed words, phrases, laughter punctuating some talk about visiting, out-loud consideration of various flights and Irie's school schedule, which Byakuran appears to know better than Irie himself. Irie can't listen, can't make any sense out of the words, but it's enough to hear Byakuran's voice, to have the reassurance of his existence at his ear. It serves as backdrop to the painful intensity of now-needless grief, the emotion crippling Irie with all the things he could have lost, all the things he somehow miraculously can still have.
Loss would almost be easier to bear. Irie isn't sure how to deal with relief.