Sage Sharadvaan was the son of sage Gouthama. He chose to master archery than the Vedas . After mastering archery, he took to a great penance which frightened Indra, the king of gods . Indra sent a divine dancer named Jalapadi to seduce Sharadvaan out of his penance. She succeeded in her mission . Sharadvaan begot a son and a daughter from her and left them in the forest to persue his disturbed penance. Miraculously, the animals in the forest did not harm the babies out of the sage's greatness .
One day king Shanthanu ( father of Bheeshma ) of Hasthipuram went on a trip to the forest and found the babies left uncared for . Out of mercy , he brought them to his palace . They were named Kripa (=mercy) and Kripi . After a few years, Sharadvaan returned and took his children with him . He taught Kripa in archery and made him an excellent professor in it. Kripi was given in marriage to Drona, who himself was a matchless professor of archery , instructed by sage Agnivesha and sage Parashuraama. Thus , sage Sharadvaan seems to be a peculiar personality, favoring archery so much that he not only adopted it as his dear faculty but taught it to his son and chose such a son-in-law as a fitting archer as he himself was !
Kripa had been in the court of the Kourava kings since his childhood. He was the primary teacher of archery to the princes there. After the advent of his brother-in-law Drona, Drona was given the honor of professorship.
In the war, Kripa naturally stood on behalf of his patrons - the Kouravas, despite his favor towards the Paandavas . He opposed Karna for his unruly behaviour and misleading the king into dangers by his wrong advice to maintain enemity with the Paandavas. During the war , he was always given a lead role. He was, almost, never defeated. Yet, it is strange to note that he had not claimed the lives of any notable person in the war !
He was one of the trio that remained on their side after the war and he took part in assisting his nephew Asvaththaama in totally destroying the Paandavas' camp in the night of the 18th day.
After the war, he remained in Hasthipuram with the Paandavas. Like Drona, he too was referred to as Aachaarya (=teacher). He was believed to be a chiranjeevi ( immortal) .
His neutral attitude was commendable. He was probably one of the few blemishless persons of the epic.