Guidance had given a moonstone pendant to C'rizz, that matched his own. The pendants were two halves of a key that opened the gateway between the Divergent Universe and the N-Space. Rassilon stated that Guidance's reason for existence was to get those pendants to him at the right time. (AUDIO: The Next Life)
Guidance was an elder of the Church of the Foundation on Eutermes, where he taught his son C'rizz. When the Kromon sacked the village, C'rizz assumed he was killed. In reality, Guidance survived the incident and continued as a teacher, eventually becoming the spiritual leader of the Church. Daqar Keep then purchased the Church and used it to find the site of the original Foundation, where the religion had started. With Guidance's help, he found it.
Not wanting the secrets of the Foundation (in reality Rassilon's Foundry) to fall into Keep's hands, Guidance pretended to take a long time to find the Foundation (a fact that Keep and Perfection were aware of but unconcerned about). When the TARDIS crew arrived, Guidance approached his son and told him the secrets of how the Eutermesans' personalities change to suit the people surrounding them and of how the whole universe ran in an endless cycle. Then he "purged" the supposedly blasphemous ideas that C'rizz had picked up by half-drowning him, hoping to snap his son back into the Church's training.
Guidance then went with C'rizz to the Foundation, where they met up with the Eighth Doctor, Charlotte Pollard and Daqar's wife, Perfection. Shortly after entering, Daqar Keep forced his own entry and murdered Guidance by creating a pair of vultures out of his body that tore Guidance's eyes out. He died proclaiming that all he had done was right. (AUDIO: The Next Life)
The Eutermesans were physical and psychological chameleons, easily influenced — a fact that Rassilon used to his advantage in plotting his escape from the Divergent Universe. As such, Guidance was a religious zealot. In entering the Foundation he believed that he would be meeting his creators. Putting the Church above all else, he almost killed his own son when C'rizz started thinking that the Foundation was not all Guidance claimed. He almost openly despised Daqar Keep even though (or because) Keep had purchased the Church with massive amounts of money. He also disliked Perfection, calling her the Doctor's whore on one occasion.
Unlike most other Eutermesans, Guidance was aware that their species' personalities moulded to fit the people around them, yet it still never occurred to him that he was being manipulated by Rassilon, who was the original creator of the Church. He also knew that the most adept Eutermesans could not only change the colour of their skin but also their texture. Being highly adept himself, he was able to camouflage himself to the point of almost being invisible, even to his son's eyes. (AUDIO: The Next Life)