When the Doctor and Charley first arrived in the Divergent Universe they found themselves in one of the Divergence's experiments, namely a forced evolution chamber. In order to keep up with the evolutionary cycle they had to physically merge with each other. Eventually they were able to break the cycle and separated from each other but all the data on their "union" was being automatically recorded and copied into an ever changing creature that they had been feeding on. Even when the Doctor and Charley left the creature kept on changing until it eventually became Daqar Keep. Keep was what the Doctor and Charley would have become if they had stayed joined. (AUDIO: Scherzo)
While the Doctor and Charley wandered around Bortresoye, Keep made his way to the Divergence's centre of operations where he found that the Divergence had withered and died under the constant torment of the cycle of the Divergent Universe. And so he absorbed them, taking on all their knowledge and power. As a result he became a constantly shape-shifting entity that was also able to create separate creatures from his own form. Assuming the Divergence's authority he commanded the Kro'ka to allow the Doctor and Charley (and later C'rizz) access through the numerous experiment "zones" on Bortresoye. As the group travelled, they brought new ideas and concepts into a stagnant universe.
It was believed that Keep spent a large amount of time away from Bortresoye in the rest of the Divergent Universe, as he was later discovered to have become the richest man in the ninth galaxy. At some point he married the mysterious woman known as Perfection.
Keep's plan culminated on a blue moon that had been moving about the Divergent Universe, somehow destroying everything in its path — the Doctor theorised that it was Rassilon's creation, the one that ensured that the Divergence remained stuck in a mobius loop — where he had been informed by Guidance that the original Foundation was located. What Guidance didn't know was that Keep knew that the Foundation was actually Rassilon's Foundry, ergo the way back into the main universe. Having absorbed the dominant species of the Divergent Universe he wanted to absorb the dominant species in this universe and the next and the next, so all life would forever be preserved inside him.
Keep, Guidance and Perfection were all on the blue moon when Rassilon, the Kro'ka, the Doctor, Charley and C'rizz arrived. Their arrival was significant partly because Keep was angry at Perfection's flirtatious relationship with the Doctor but also because C'rizz possessed half of the key to the Foundry (the other half was held by C'rizz's father, Guidance). He accused the Doctor of murdering a native child and hunted him and Perfection through the jungle to the Foundry. When it was opened he murdered Guidance but was briefly overcome by C'rizz with Rassilon and the Kro'ka's assistance. Then he pursued the trio into the Foundry, revealing to Rassilon that this was the eighty-fourth time that Rassilon had attempted to escape the Divergent Universe and that each time he had been caught by the Divergence (and later Keep) before being sent back to the beginning of the universe with his memory erased. Keep promptly dispatched Rassilon and the Kro'ka to the beginning of the cycle again, this time with their memories intact. Before he could enter the main universe however, Perfection incapacitated him with a harpoon with a regenerative inhibitor in its tip. Then Perfection was revealed to be possessed by the entity known as Zagreus. As Zagreus wanted to enter the main universe as well (even though it would result in the destruction of history), Keep surreptitiously adopted the shape of the TARDIS in order to trap Zagreus inside his body. The ploy succeeded and he restrained Zagreus long enough for the Doctor, Charley and C'rizz to escape with the real TARDIS. Now trapped and all hope of escape gone with the TARDIS, Keep proposed to Zagreus that rather than fight they should renew their Wedding vows. Aside from being an extremely diverting experience, as the two of them were the greatest beings in their universe they would be able to "put a bit of stick about" and really show everyone who was boss. Zagreus agreed. (AUDIO: The Next Life)
Despite being created from the Doctor and Charley, Keep was an incredibly dangerous being with few scruples and a vindictive streak. He was known to have abused Perfection to the point of driving her to suicide. He ordered the Doctor's execution readily despite the Doctor being his "father". He spoke fluent French (as Charley learned it from her Uncle Jacques), which caused the Doctor to suspect what Keep was, as no one in the Divergent Universe could have learned it. He also inherited from his "parents" a peculiar taste for old-fashioned and decidedly Earth-centric concepts such as hunting, taxidermy and howdahs on elephants. It was known that he had a huge ego and in fact only indulged in the practises of the Foundation because he enjoyed being a religious leader. He was eager to remarry Perfection/Zagreus, perhaps out of respect for how powerful she was, in spite of the two of them being deadly enemies minutes earlier. (AUDIO: The Next Life)
After absorbing the Divergence, Keep developed a peculiar ability. Not only could he shape-shift but he could also grow other creatures out of his body as extensions of himself. At two points he adopted the form of a swarm of insects. He also grew several animals out of himself, such as a group of crocodiles, a herd of two-trunked elephants, several humanoids and a pride of tusked jaguars. When he took on the shape of the TARDIS, he somehow made himself dimensionally transcendental, again suggesting great power. All this made him virtually impossible to kill or even harm (after being shot in the foot with a shotgun he just regrew it) but he was seen to be affected by Rassilon's particle wave disseminator and a harpoon with a regenerative inhibitor reduced him to a puddle of something messy (if only for a short time). (AUDIO: The Next Life)