According to the book Contact, Caleb said that growing up had always been a shadow to him. His parents ( Samuel and Elaine Anderson ) didn't socialise with him often. As a result, this gave Caleb a deep sense of loneliness and a need to open himself
Joining the Morphers
Return with a vengeance
It did take a while for Caleb to return, but under Adam for the first time. Adam tells Caleb to swear allegiance to him and gives him an offer to eliminate the Morphers. As told, Caleb attacks his former friends while they are out shopping.
Redemption and subsequent "death"
At the start of the series, Caleb is shown to be a fearless, but sometimes reckless member of the team. He is able to adapt to tough situations, and is quite an excellent fighter on the battlefield, making him one of the expendable members of the team. However, Caleb's has several weaknesses that became evident during the second half of the series, as most of the time, he is impulsive, lacks trust, and is often rash about his own actions, which he has often put up a facade to hide it from his teammates.
Among the Morphers, he is closest to Rachel, as she is the only one who could relate to his past and is much more understanding than the others, which Caleb would later exploit. He told her about his past, but Rachel still harbors attraction for him. He gets along well with the other Morphers except Rueben, who he constantly argued with when it comes to strategizing and questions his leadership at times. Caleb and Rachel are often happy and fun-loving together and has went to a date once.
Another of Caleb's weakness is his naivety, which Adam used to trick him into joining him, stating that it's the only way to win the war. He felt betrayed with Reuben's affections over Rachel, which was another reason why he betrayed the Morphers. As a result, he began to work to destroy his teammates from within. Just as romance with Rachel grew, his motives were exposed and he turned to Adam, the only who he believed, could trust him. The Morphers, still holding some affection for their former member, were naturally caught off guard, and were hesitant to stop him, which gave Caleb the upper hand and in the second round, due to reinforcements sent by Adam. The Morphers, knowing the battle could not be won, began to retreat.
While the other Morphers lost faith in Caleb, Rachel still had faith and believed that he could be redeemed as she knew a lot about him. She also pointed out that she never gave up when Reuben joined Adam. Determined to redeem Claeb, Reuben reminded him of his past, which Caleb shrugged it off, stating that "it's no small matter" . Deciding to give Caleb one last chance, Rachel made Caleb see the error of his ways to which she succeeded. In his first (and only) act of true heroism, Caleb rescued his friends and presumably dying in the process.
Relationship with the other Morphers
Rachel- Before the two became Morphers,
Nick- Nick and Caleb weren't on best terms at the start of the series, but over time, the two would often hang out and cooperate during battles together.