Who became one in spirit with David and loved him as himself?

The correct answer is Jonathan, who is known for his deep and loyal friendship with David. The biblical account describes Jonathan as the son of King Saul, and their relationship is portrayed as one marked by profound affection and commitment. In 1 Samuel 18:1, it specifically states that "the soul of Jonathan was knit to the soul of David," emphasizing the intensity of their bond. This relationship is notable for its mutual respect and support, particularly as Jonathan recognized David's anointing by God, despite the implications for his own claim to the throne.

Jonathan's love for David is further illustrated in various instances where he protected David from Saul's attempts to kill him and facilitated their friendship amid difficult family dynamics. This connection not only highlights the theme of friendship in the narrative but also serves as a significant contrast to the hostility David faced from other characters, particularly Saul and Absalom, who are associated with conflict and opposition rather than the loyalty Jonathan exemplified.