[BL] Due to a rare condition, Vince’s end of the red string of fate is tied around his neck, while his soulmate's, Jack, is tied around his finger, like it’s supposed to be.

Theory says that if they "sleep" with someone that isn’t their soulmate, the string tightens on the other end, letting your soulmate know exactly what you are doing.
When Jack feels his string tightening, he feels heartbroken, and starts to sleep around with everybody as revenge, not knowing Vince was a victim of abuse.

When they finally meet, Vince is already suffocating.

or -
Love and fate's hopes for humanity were way too high and all they got was disappointment

Singularity: The Red String Around Your Neck

Jack can't believe what he hears. He turns back and the boy is still crying, but something in his eyes tell him he does need him. He needs him close. 


So Jack pulls him up to his feet and hugs him, tight. Vince immediately melts into his arms. 


Jack cries softly, not believing he's finally holding Vince after so long. 


"Give me another chance, Vin." he says, hands going through the other's hair. 


"I'm not asking you to love me, I- I’m just asking to be a part of your life again. Please. I can be better, you know? I can be good. So you’ll want to have me in your life, too." 


Vince sobs against him, and Jack kisses the top of his head. 


"I could handle being away from you because that's what you wanted, so I swallowed my pain and did it. But I can't do it knowing it’s making you suffer too.” 


Vince sighs, trying to calm himself down. 


Chapter XXIII