Finding the TARDIS
Alydon discovered the Doctor's TARDIS in the Petrified Forest. He left a case of the Thals' anti-radiation drug for the TARDIS crew and later made contact with Susan, giving her an extra case of the drug and also his cloak. Alydon did not entirely trust the Daleks and gave Susan more drugs in case his people's ancient enemies did not share them with the time travellers as they had promised. His cloak, being made of non-conductive plastic, proved instrumental in the TARDIS crew members' escape from the Daleks, letting them warn the Thals that they were walking into a trap, albeit not before the Thal leader Temmosus was killed.
Alydon succeeded Temmosus as leader as the Thals, but even after this act of vicious treachery by the Daleks, he refused to lead his peaceful people into war against their ancient enemies. He argued it was war that had turned their world of Skaro from a paradise to a wasteland.
Alydon was in love with the Thal woman Dyoni. The First Doctor and Ian Chesterton orchestrated a ruse in which they threatened to hand Dyoni over to the Daleks for experimentation. This provoked Alydon to fight to protect her. He was convinced that he would be willing to fight for something and must if the Thals were to escape extermination. (TV: The Daleks)
Against the Daleks
While Ian and Barbara Wright led a party of Thals to find a way into the Dalek city via the water supply, Alydon worked with the Doctor to disable the Daleks' surveillance equipment. Although the Doctor and Susan were captured, their plan worked. The Thals gained entry to the city. They fought the Daleks in a pitched battle that ended in victory for the Thals. After the TARDIS departed, Alydon settled into a life with Dyoni and worked with their people to rebuild Skaro. (TV: The Daleks)