Cett is described to a rather crude individual, a man who constantly uses profanity and threats of violence in his language. Cett was crippled as a child due to a disease that took his legs. Unable to enact violence himself, Cett was forced to find other methods of intimidation. He was born noble, but did not fit in with the rest of noble society, due to both his temperament and lame legs. It is noted by Slowswift that Cett was a fine poet before politics stole him away.
Cett is first mentioned by Hammond when he reports that he had identified the Allomancers that had attacked Vin. Elend initially assumed that they might be people he'd know, as he believed his father had sent them. Ham, however, reported that they were westerners, and that it was unlikely Straff Venture had done any recruiting out there. He postulated that Cett had sent his assassins to take out Vin and Elend so that he could take Luthadel himself.
A few days later, after Straff's army had arrived outside of Luthadel, Elend received a report that a second army had arrived. Elend had hoped that they would help them, but nobody else shared his hopes. Minutes later, a lone rider rushes away from the army, and Vin identifies him as Breeze. In order to save him, she jumps over the wall and Pushes herself out to him. She kills the soldiers that give chase to Breeze and gets herself back into the city. Breeze tells her and Elend that he had tricked Cett into bringing his army here in order to make it a standoff between him and Straff so Luthadel would be safe for the time being. Cett had actually been poised to arrive first, but Breeze has slowed his army down by poisoning their supplies.
As part of the three-way standoff, Cett laid siege to Luthadel alongside Straff in order to pressure Elend into siding with one of them. Dockson, as head of Kelsier's crew, had suggested to Elend that they try to reason with Cett, as he would not be as bad a ruler as Straff. Elend, however, wanted to try and pit Cett and Straff against one another and play both sides until both warlords were wiped out.
Cett's daughter, Allriane, snuck into the city to find Breeze one night during the siege and Breeze was flustered. Elend picked up on the opportunity to return Allriane to him in order to build relations.
When Elend and Straff conversed in Straff's camp, Straff told and told Elend that he and Cett had an alliance, as Elend tried to trick his father into riding against Cett. Elend picked it out as a lie later.
An Assemblyman named Philen smuggled Cett into the city after Elend was deposed as reigning monarch. When nominations for king were called, Philen stood and nominated Ashweather Cett. Vin and Breeze were shocked to see Cett in the crowd. Vin learned that he had been crippled as a child, but was suspicious of that being a cover story to hide his powers as a Mistborn. He made threats against Elend and the rest of the Assembly that unless they made him king, or if they tried to hold him hostage, his army would slaughter them all. Cett asked to take up residence in the city until the official coronation was held, and was allowed to remain in Keep Hasting with one-thousand soldiers and staff.
Cett's son, Gneorndin, invites Elend to a dinner the night he arrived in the city. The night of that dinner, Elend shows up, though he is not a king that can be held hostage. Cett asks Elend if he would support him in exchange for giving the skaa the freedom that Straff would not. Cett brushes off any at all comments or offers regarding Allriane, claiming that he really didn't care. When he realized that taking Elend captive would only hurt his attempt to be elected king, he allows him to leave.
Cett appears at the next Assembly meeting, attending with a smug pride. When a group of assassins attack shortly before the voting begins, Cett is injured. He does not attend the meeting at Penrod's mansion because he had to treat his wounds.
When Elend returns from the koloss camp run by Jastes Lekal, Vin goes on a vendetta attack on Keep Hasting with Zane in order to kill everyone they could find in so whoever took charge of Cett's army would be to scared to attack Luthadel. After killing three-hundred men together, Vin finds Cett with his son. Gneorndin feebly attacks her, but she brushes him aside carelessly. Cett limply attacks her when she prompts him to do so, but otherwise just tells her to finish him off. When she spares him, Zane enters, wanting to kill him and his son. Vin convinces him not to, and they leave separately.
Cett and his army pull out of Luthadel the next day and retreat into the Western Dominance. Allriane catches up to them a few weeks later, and she tries to get him to return to Luthadel, but he says to do so would mean that they would have to surrender to Straff, since they could not go back to their own city. Nevertheless, the army does move back into the Central Dominance to observe events as they unfold.
When Vin attacked Straff's army and killed him, Cett pondered waiting until the battle was over to march in and take the city, but Allriane told him that he would have to help fight against Straff if he wanted to get her back before she ran off. Cett realized that he had never really hoped to take Luthadel and the atium with the forces he had, and had only ever wanted to see if the girl who had killed the Lord Ruler was as powerful as the stories claimed. He ordered his army to charge against the remains of Straff's forces. Sazed saw this as something prophesized about the Hero in the Terris religion, where kings would ride to the aid of said Hero.
Cett arrived in the center of the army at the end of the conflict and was forced to kneel before Vin and pledge fealty to Elend or face death. While waiting for the new emperor to return to Luthadel, Cett argued with Penrod and Janarle (whom had both knelt before Vin as well) about moving to conquer the Western Dominance immediately. With Vin indisposed and unable to deal with their squabbling, Sazed had to remind them of her power to keep them from snapping at each other.
Following the Siege of Luthadel and surrender of three leaders to Elend, Cett seemed to have taken the role of a military advisor and general. Working with Ham to manage the bulk of Elend's army, Cett became what Vin believed to be the successor of Clubs, the previous military general in Kelsier's crew.
His first appearance is at the crew's final meeting, where the crew is informed that the army will march into the Western Dominance to either conquer Fadrex City or deal with the obligator leader so that the contents of the city's storage cavern could be given to the Central Dominance. Cett was happy that they would finally get around to getting his city back, but was cautioned by Elend in that he might not get control of the city when they were done. Cett had little to say about Kelsier when Elend asked the crew about him, other than how he was inspiration to many skaa in the Western Dominance.
Cett was hasty to expose the soldiers to the mists in order to inoculate them to the affects that some suffered while others did not.
Cett had a silent agreement with Elend about their only option in taking Fadrex City: siege. At the westerner's suggestion, Elend authorized a force of ten-thousand soldiers to roam around the countryside and block roads and interrupt proceedings in local villages, but left strict orders for them not to pillage or kill any civilians. Cett handpicked a few of his informants in the city and gave the list to Vin. The first on the list was a nobleman named Slowswift, who was surprised to hear that Cett was alive. He regarded Cett fondly as a fine poet.
On the night of the ball at Keep Orielle, Cett did not forcefully object to Vin and Elend going to the ball, something that surprised Elend. He asked if he would be in charge should Elend and Vin both died in the city. Elend told him that if he and Vin died, he was charged with seeking out Sazed to tell him that he would be in charge, since whoever could manage to kill two Mistborn at the same time would come for him next. Ham was very uncomfortable with Elend allowing Cett to remain in charge, but the emperor reassured him that Cett was a better man than he let on.
After returning from the ball in Fadrex, Cett berated Elend for socializing with the people, believing that this would prevent Elend from attacking should it become necessary. Elend pointed out that when Cett failed to socialize and make alliances when he was in charge, he was thoroughly ousted from power, but Cett was adamant in his philosophy that the noblemen Elend had met were their enemies and that enemies could only be seen as numbers lest he grow too compassionate with them. Cett reports miserable tidings in the camp with several raids being aborted when the soldiers hadn't the heart to harass the starving skaa and numerous fistfights around the camp after they were all put on half-rations. Demoux, fully recovered from the mist malady he had first suffered sixteen days earlier, walked in, only to be mocked by Cett for falling ill for so long.
When Yomen's forces launched a morning assault on Elend's camp, Cett organized the soldiers into battle alongside Ham. Both were astounded and saddened by the news that the assault had been a diversion to keep the soldiers from noticing all of Elend's koloss embroiled in a blood frenzy and attacking each other.
Vin discovered the way koloss were made and Elend shared this knowledge with the group. Cett grew frustrated with the discussion as he felt it was pointless since they were not planning on making new koloss out of their soldiers, but Elend determined that it was important because Hemalurgy united kandra, Inquisitors and koloss, and that such was evidence that there was a force controlling the koloss. He ignored Cett's concerns, simply resolving to let Vin deal with it and focusing on Yomen's army.