Just picked this up - so Bhishma was cursed for abducting Amba. Certainly a flawed individual.
Santanu, king of Hastinapura, was married to the beautiful Ganga, who was the river goddess in disguise. She agreed to marry him as long as he never questioned her actions. Over the years they had seven sons, but Ganga threw each one into the river. Santanu was distressed but he kept his promise. Finally, when their eighth son was born, Santanu asked his wife who she really was and why she had done this. Ganga revealed herself and told that her children had once been celestial beings, but were cursed to become human. She had ended their punishment quickly by drowning them immediately at birth. But since Santanu had questioned her actions, she left him, along with his last son Devarata.
Devarata is better known by his later name Bhishma. He receives this name, which means of terrible resolve, after vowing never to marry or have children. His father wanted to marry again (Satyavati, mother of Vyasa), but the conditions of the marriage were that the second wife would be the mother of a king someday. Honoring his father's wishes, Bhishma makes his vow, guaranteeing that neither he nor a son of his will challenge the claim to the throne.
Years later, one of Bhishmas half-brothers dies in battle, and the other becomes old enough to marry. On behalf of his half-brother, Bhishma abducts three sisters and fights off all their suitors. On returning home, he learns that one of the sisters, Amba, had already chosen a suitor. Bhishma allows her to leave, but her betrothed does not want her any more. Now abandoned, she returns to Bhishma and demands that he marry her. Ever faithful to his vow, Bhishma refuses. Amba then vows that one day she will kill him, even though the gods have granted Bhishma the power to choose the day of his death, because of his vow.
I will get back to this discussion in a day or two. Urgent responsibilities are demanding my attention!
(All the sons of Ganga Ma who she threw into the river returned to the heavenly planets to be re-instated in their positions; they had to take birth just once on earth for some misdeed which I can't remember at the moment.)