|“||Sergei have new toy! Training is going to be a lot more fun.||„|
|~ Sergei to Hu.|
Sergei is the main antagonist of Illumination's 10th feature film The Secret Life of Pets 2. He is the cruel and abusive Russian owner of Sergei's Circus of Fun and Hu's former owner. He is also Max and Snowball's arch-nemesis.
Sergei is a circus owner who is evil, cruel, angry, short-tempered, and loud. He threatens and torments animals out of greed.
Chloe and Snowball meet Shih Tzu Daisy, who explains that she needs Snowball, who dreams of being a superhero, to assist her with rescuing a White tiger cub named Hu. While on flight back to the city, Daisy encountered him being held captive by Sergei. Daisy and Snowball sneak in and find the circus Hu is in. They witness Sergei torturing Hu while trying to practice performing a water diving trick using a whip no matter how scared the cub is; much to their horror. After failing to perform the trick and being caged, Sergei threatens to turn Hu into a rug unless he performs well the next day during training and charges his pet Wolves to guard him with their lives. Luckily, Daisy and Snowball free him after subduing the wolves in a long fight.
She and Snowball take him to Pops' apartment first. Pops reluctantly lets Hu live there at first, but due to his destruction of the apartment afterward, Hu is kicked out and relocated to Max and Duke's apartment. Around the same time, the family returns from the trip. Sergei and his wolves track Daisy down and capture both Hu and Daisy. Sergei escapes in his train moving for the circus in which Snowball, Max, and Norman pursue while contacting Gidget for assistance in the chase. Gidget and the cats take their owner off in her car, in pursuit of the train.
Max and Snowball defeat the wolves and Sergei's pet monkey while freeing Hu and Daisy respectively. Max, using his newfound bravery Rooster gave him, successfully infiltrates the train locomotive Sergei is in. The rest of the animals join in and attack Sergei. Sergei's conductor then stops the train and Hu and the others plan are about to return to New York but Sergei stops Hu from escaping by restraining him with his chain collar/leash and is just about to shoot them all until he is hit by The Cat Lady, knocking him out.
Afterward, he possibly was fired from show business and arrested for his crimes.
It is unknown if he will escape prison and get revenge in a third film sequel.
- Sergei is the first antagonist in The Secret Life of Pets film series to be a human, whereas Snowball and the Flushed Pets are all animals.
- He is the third villainous character to be voiced by Nick Kroll, following Douche of Sausage Party and Tippy Tinkletrousers from Captain Underpants: The First Epic Movie.