Forget Me Not (SkyNani Vampire AU)

Nani is a ruthless vampire whose thirst for power made him spread chaos across centuries until his reckless actions resulted in him losing the man he loved more than anything in his life.
Living with guilt and agony, he had almost lost the last ounce of humanity he had in his heart until he decided to adopt the 3-year-old little girl left by her parents in front of his door on a cold winter night.

15 years later, Prim grew up to be a beautiful young woman and started causing trouble to her protective dad who was barely allowing anyone to approach her until one day, she started talking about this classmate of hers named Sky, a boy that she became particularly obsessed with because of how perfect he was. Nani finally accepting to meet the lucky guy, was surprised by the fact that this man was a split image of his first and only love, Saint. Not only that, the boy started trying to get uncomfortably close to him, wanting to break the ice between them but it only made Nani's broken heart more troubled.