Alright, how about this? Was reading some manga and saw something about succubi and I was like that's cool and started thinking about a novel idea ... here goes.
The main character is born into a world of magic and swords. Little boy who has brown hair and black eyes. His life goes smoothly till he turns 8 years old, he's above average in everything but not quite genius or monster level, but once he turned 8, things around him started to change. His face and body became more slender and flexible, while the lines of his face became softer as though he was a work of art. His originally black eyes started getting pink deep inside them which wasn't noticeable till he turned 10 and started training in magic and swords. His skin began to get paler and paler and his hair started turning deep and dark black as though it both absorbed all light and reflected light at the same time, it started at the roots of his hair and by the time he turned 10, his hair was half black and half brown with his eyes a noticeable pink tint in them with his skin being completely pale white as opposed to the rest of his family's tanned skin. His entire family was confused and taken aback by the changes in him. He was getting shunned by his peers, while his seniors still cared about him they were in contact with him less and less, afraid of contracting the "sickness" he had gotten as it made him look weaker than he was, even though he was just as healthy, if not more, than he was before the changes in him had taken place. When he turned 10, he along with all the people that had turned 10 that month, got their talents and attributes tested. When the MC got tested, it was revealed that he had an absurdly high affinity for Darkness, Illusion, and Life, some of the rarest elements as they were ranked higher than the five elements; Fire, Water, Wind, Earth, and Metal with Illusion, Space, Time, Darkness, and Light being higher order affinities. As he trained and trained he eventually reached a bottleneck and couldn't advance anymore. Even after training and trying to break through with life and death battles, medicinal pills, and external help he couldn't break through no matter what. One day, after being laughed at and mocked by his peers he leaves his household and wanders aimlessly through the town. He walked into an alleyway to cut across a few streets and get to his favorite place to eat, when he was knocked out and kidnapped by people from the gangs on the street, thinking with his mixed hair, which they assumed was dyed, and frowning face that he was there to pick a fight and was intruding on their territory. When he woke up, he was bound on a bed naked and a girl walked in wearing just her underwear, licking her lips and force fed him a pill that turned out to be an extremely strong aphrodisiac. She said that with his slim, flexible, and soft figure he was just her type and she had sex with him, albeit forcefully. After he climaxed, he felt energy coming into him from the girl he just had sex with that was panting, laying on the bed. He turned to her and saw that she was aging very rapidly and couldn't even stand up anymore, till she turned to dust and as she turned to dust, he felt something click in him. As though a new power was awakening, he felt it, spreading from his lower back around his tail bone, to his shoulder blades, eyes, and mouth. With new found strength he broke the restraints binding him and looked for clothes to wear but could only find a hooded black robe. He peered out the door and looked around for any enemies but couldn't see any in sight so he ran all the way home and slipped by the guards into his courtyard and straight into the bathroom. As soon as he got into the bathroom, he slipped off the robe and let it fall to the floor, he was stunned. In place of the thin, flexible youth with mixed hair and black eyes with a shade of pink, was a taller youth with muscles that fit his slim build perfectly, not too big and bulky, but not too small to not be noticeable, just perfect. His skin was now a pure milky white, like it couldn't be tainted no matter what. His calloused hands now were slimmer with longer fingers, that felt smooth as silk. His hair was now deep, dark black and absorbed light perfectly. His eyes, which originally only had a pink tint, now were a beautiful shade of pink as though they were cherry blossoms. His teeth which were white, had now turned even whiter and he now had fangs which seemed to secrete a certain sweet tasting liquid at will. As he turned around he saw on his tailbone he had a heart shaped tattoo that ended in a point sharp enough to pierce metal and on his shoulder blades he had tattoos of bat wings. As he examined himself, he suddenly sniffed and realized that his body was giving off a seductively sweet smell that seemed extremely appetizing. After his inspection, he got worried and ran to meet with his parents and told them about what had happened to him. Hearing this his parents got startled and looked at each other with a solemn air between them and they started talking. They told him that he apparently had an extremely pure bloodline, from the long extinct race of succubi, and that they had tremendous talents in seduction and magic, but that there has never been a male of their species which was why he was never suspected of being one. Hearing this the MC was confused about why they were extinct and asked his parents. Apparently, succubi were known for charming people to get what they want and when they couldn't would engage in mass slaughter, but that was only the official reason. The real reason was to get the liquid they produce from their fangs. It's a divine healing medicine when used in combinations with other herbs, but its also an even stronger aphrodisiac, that when used before sex will make a person feel so much pleasure they will feel as though they had reached nirvana. Knowing this, his parents helped him pack all his stuff, along with all the training manuals and books he would need to survive and grow strong enough to protect himself, because he couldn't stay at his house otherwise his greedy family members and elders of the family would sell him off to get a profit for themselves. So he left on a journey.