Abel, like his older brother Cain, was one of the first children, as well as being the second son of, Adam and Eve, the progenitors of the human race. Surprisingly, little is known about Abel throughout his life, but according to those whom known him more than the scholars depict, he was known to be righteous and one of pure heart and devotion to those who are deserving of it.
Abel lived a relatively peaceful life alongside his brother Cain, however, due to Abel's love for his elder brother, he was unfortunately naive to see that Cain was beginning to show signs of envy from the fact that God was favoring Abel over him. Despite the seemingly act of favoritism, however, Abel showed no signs of pride for it, and would never boast of it towards his brother. Instead simply treating him as an equal and even would request that God would allow Cain's crops to be eternally nutritious for centuries to come. Yet despite all that, this did not quell Cain's jealousy.
Things eventually took a turn for the worst when the two brothers presented their gifts to God; Abel's was a lamb since being a shepherd, and Cain's being wheat since being a farmer. God made His choice clear by burning the lamb and leaving Cain's gift. Later on Cain, now under the influence of the mark and his rage, lead Abel to a remote area with the younger brother completely unaware of his fate. And sure enough, his fate has been sealed as Cain fatally struck Abel and thus killing him. Abel's death was cemented as being the first ever murder to be committed by man.
Not only that, but when God took wind of this event, he cursed Abel's blood as it soaked Cain's feet and the Earth itself. The curse would forever be soaked into the roots and soil of the Earth, and would remind that any who so foolishly commit the act of killing one's brother out of jealousy would suffer a fate some consider worse than death. Abel's blood is said to be the manifestation of vengeance, crying out for the destruction of Cain's seed.