Some of their past is mentioned in the ninth book. Kevin remarks that "everywhere I go, people say "ooh look there's Kevin the ambidextrous freak" and nobody wants to know them. They are all disabled or impaired - however, it is only Hugo who has a real disability. He is a hunchback. Colette is a contortionist, meaning she can twist her body in any way, and Kevin is not really disabled at all; just being ambidextrous, and for some reason he thinks V.F.D. wouldn't accept an ambidrextrous man, despite their recorder himself being ambidextrous.
In the carnival
Count Olaf often came to the Caligari Carnival to visit Lulu to ask her where the Baudelaires were, in his quest for their money, also to claim other fortunes such as the Snicket and Quagmire inheritances. "But never a penny does Lulu see," which says the carnival is poor. The henchmen are eager for fame and respect, so when Esme Squalor offers them work as Olaf's henchpeople, they immediately defect, but are somewhat hesitant about murdering Lulu, which Esme wants due to her jealousy of Lulu's love rivalry with Olaf. Esme seduces the henchmen into killing Lulu saying its just what they do every day. At the show, Hugo, Colette and Kevin try to outdo themselves to please Olaf and offer to work for him, saying they could be better than the hook-handed man. Hugo, Colette and Kevin even shove themselves to the Baudelaires to throw them in, but the lions still get their meal nonetheless when Lulu herself falls in, pulling in the bald man from Olaf's troupe with her.
On Mount Fraught
Hugo, Colette and Kevin then join Olaf and drive up the mountains with him. But Olaf works out the Baudelaires are in disguise and he orders Kevin to cut their harness and kill them by sending them crashing in a ravine. Kevin even smiles in glee before cutting the rope. Then the Baudelaire caravan does fall down, but Violet stops it at the last minute. The henchmen don't think they have survived and continue with the captive Sunny Baudelaire and reach the peak. There, they cruelly order Sunny (who is only two) to set up tents in the freezing dark.
Then Hugo, Colette and Kevin bicker throughout the stay, complaining about living together, and Count Olaf criticizes Colette's dental floss, saying you only need it to strangle someone, implying he wants them dead. Then Count Olaf yells at Sunny for making cold breakfast - without fire - on a mountain, and then his bosses arrive, the man with beard but no hair and the woman with hair but no beard, to tell him about their victories. Their presence makes Hiugo, Colette and Kevin uneasy, but they talk about the bosses when they've gone, and wonder who they are. Then, to increase their villainy, they make Sunny boil fish for them, despite her only being two.
Later, Hugo, Colette and Kevin are left on the peak when the Baudelaires escape. They lure some captives into a net for Olaf's gain. Then they are left to chase after the orphans with Olaf.
At the hotel
In the Hotel Denouement, Hugo, Colette and Kevin are given humiliating and unpleasant chores to do - such as Kevin being a washerwoman, wearing a humiliating wig and robe. When they all meet, having viewed each other without knowing each other's identity in the hotel, Klaus comments that Kevin could be with them and be noble. In an argument, Hugo, Colette and Kevin report that the villains have won and that the Baudelaires actually helped them. But then things go wrong when Olaf shoves a gun into the Baudelaire's hands when Mr. Poe arrives, causing the gun to go off and kill Dewey, the assistant manager. The henchmen accuse the children of the crime, and attend the V.F.D. trail. Later, Hugo, Colette and Kevin are wandering the hotel looking for the orphans when Sunny sets it aflame to tell V.F.D. they have failed; and it is believed the henchmen die in the flames.