Trust AU
Seraphim have left the human realm, leaving behind them a group of humans blessed with their powers. Those people call themselves Malakhim. In order to use their power, a Malak must bond with another being. Like a flower, the power will takes root in the vessel's soul, feeding on the vessel's trust for the Malak. If there's no trust the roots won't expand and the Malak can never leave their vessel's sides or the flower will wilt. If the Malak uses their power despite the lack of trust, the flower will bloom using the lifespan of its vessel.
Once a bond is made, cutting it will most likely result in the Malak's death; a flower cannot survive long without its roots.
Humanity came to reject Malakhim, deeming them responsible for the Seraphim's disappearance. So the Malakhim ran away to save their lives, going on an never ending journey and letting history forget about them.
Centuries later, the world awaits for the return of the Seraphim, believing in the old tale of the Shepherd, the messiah who will one day open the door to the heavenly realm.
Sorey is a Malak, one of the very few left. Mikleo is the heir of the last Shepherd, born left handed and therefore believed to be blessed by Seraphim.
Sorey is an optimistic and naive person despite living a rather lonely nomad's life. Mikleo has always been surrounded by shady people trying to obtain the Seraphim's blessing through him.
One day as he is travelling with his escorts to Lohgrin, Mikleo crosses Sorey's path. Stricken by Mikleo' beauty, Sorey accidently bonds their souls.
...No really, he didn't mean too, he was just so tired and thirty (no not like that Zaveid oh gods why did you have to put it like this in front of Mikleo now he's going to think I'm a creep), and suddenly there was that beautiful, gorgeous person, with a water like aura, holding out their left hand to him, Sorey thought a seraph had come for him and accidentaly released his power when he took the offered hand.