- "Dovizhdane, Katerina."
- —Alek says his final goodbyes to Katherine, Gone Girl
His protective side is shown greatly when they first arrive in England and after he has denounced his family in order to travel with Katherine.
In 1864, Aleksandar does experience a hostile-like relationship with Katherine when he blames her for their misfortunes, however, he immediately feels regret and devastation when he believes her to be amongst the dead vampires in Fell's Church.
During the events of the Vampire Diaries, Alek is still seen to be loyal to Katherine, which causes people to question and doubt his motives. Furthermore, he tries to find redeeming qualities in Katherine even when others believe that there is none. However, he admits that Katherine is a danger while she is active and plotting; and while he attempts many times to help capture and subdue Katherine, he is vehmently against killing her. When Katherine takes over Elena's body, Alek accepts that she must be killed, as he believes that taking over Elena's body has crossed the line.
- "She threw her life away for you and you won't even give her the time of day."
- —Alek about Nadia to Katherine, Fifty Shades of Grayson
When Nadia first arrives in Mystic Falls, he is distraught that Katherine doesn't want to get to know Nadia and is appalled when she acts selfishly even in the presence of her only daughter. Alek does get into a few disagreements with Katherine on Nadia's behalf, claiming that he would kill to have a child and that Katherine didn't appreciate Nadia enough.
Later, when Nadia is bitten by Tyler, Alek is driven to kill Tyler, but is stopped when Nadia admits that she had been using Matt for Katherine's sake and that Matt's friends were only trying to protect him. Alek still harbours a hatred for Tyler and is still quite bitter towards the Salvatore boys, as well as Katherine, for being instrumental in Nadia's death.
- "You are a Petrova. It's time you stopped hiding behind the Gilbert name."
- —Alek to Elena, Katerina
- "Katherine is my pain in the ass, just as Damon is yours."
- —Alek to Stefan, Plan B
- Alek: "I can feel your doubt from across the room."
- Damon: "I'm just trying to figure out if you're planning to stake me in my bed or poison my bourbon."
- Alek: "I'm not Katherine Pierce, Damon."
- Damon: "No, you're just the next worst thing."
- — Alek and Damon, Masquerade.