Iolas Blue was an acquaintance of the Second Doctor, whom he considered his arch-enemy, and knew his schedule completely.
Based on his childhood interest in butterflies, Iolas's lepidoptery extended into a fascination with the concept of chaos theory, with small details and twists leading into larger changes. To this end, he created a computer called the Predicticon, which helps him determine future events by reverse-engineering chaos theory, identifying what caused big events by working backwards to pick out the key events responsible for the bigger picture. Using this technology, he was able to make great scientific breakthroughs, such as inventing a time transporter several centuries before human science would be able to create such a device. As Iolas planned to rule the galaxy, he identified that the biggest threat to his plans was The Doctor, who would apparently kill him in his future.
With the knowledge of their future relationship driving him on, Iolas drew up a thousand-plus step plan that would end with The Doctor's death, using the Predicticon to calculate everything from where the TARDIS would materialise to smaller details such as that Jamie preferred muffins to cake, as well as helping him to construction dimensional disruptors that would prevent the Doctor simply taking off again later. Although he had plans to conquer the universe, Iolas was not a 'natural' villain in the sense that acting evil came naturally to him, drawing up a list of his plan to defeat The Doctor and rehearsing some of his moments of revelation to the Time Lord, such as what kind of stance he wanted to present to his enemies when they arrived. However, his lack of natural villainy did not make him a pleasant person, as he demonstrated his control of future events to the Doctor, Jamie and Zoe Heriot by using a time teleporter to send a sandwich with contaminated mayonnaise and a small music device back in time by a century and a few days respectively. These small actions started a chain of events that would start an interplanetary war and cause a meteor shower, killing a sports racer whose only 'crime' was that he had stolen Iolas's girlfriend at school.
When they learned what he had done, The Doctor and his companions were outraged at Iolas's actions, with Iolas's sole 'defence' being that he was not a killer as he had not actually done anything to cause the death directly. Outraged at their continued disgust, Iolas still proclaimed that they had to die in order to stop them from killing him. With four hours to go until their predicted death, the Doctor, Jamie and Zoe constantly tried to escape, but although they were able to get the TARDIS working, they were sent back to Iolas's apartment through a chain of events that allegedly started when he sent a man a copy of The Maltese Falcon, Iolas angrily countering that they weren't going to give him a chance as Zoe sobbed about how their imminent deaths weren't fair, ignoring the fact that they had only gone after him when he was an actual threat.
However, Iolas's plans fell apart when he reached the point where the Predicticon had stated that the crew would be killed by a dimensional disruptor and nothing happened. Angry at the Predicticon, Iolas marched towards it, only to slip on an oil spill that he had created earlier to trip up Jamie, which resulted in him breaking his hip. The Predicticon then revealed that, through a series of events, including the TARDIS crew damaging particular sets of controls in their earlier escape attempts, Iolas had started a domino effect that left him pinned under a hunk of plaster from the ceiling of his apartment, the equipment that was keeping the TARDIS trapped disabled, the Doctor, Jamie and Zoe back with the TARDIS and sealed away from Iolas, and Iolas's apartment building about to be destroyed by the same meteor storm he had created earlier.
As the Predicticon revealed, it had foreseen that humanity would basically end if Iolas succeeded in taking over the universe as the ability to predict the future would leave humanity without anything to strive for, coupled with the fact that Iolas was a bitter, unpleasant person who held unnecessary grudges. As a result, it had faked the prediction of the Doctor defeating Iolas in the future so that he would attempt to kill the Doctor now and create a situation that would lead to his death. Suggesting to the Doctor that he ponder the irony of defeating an undefeatable villain merely by turning up, the Predicticon told the Doctor and his friends to leave, the Predicticon exploding shortly after the TARDIS departed, taking Iolas with it. (PROSE: Lepidoptery for Beginners)