This is an article focused on Kowalski's relationships throughout the TV and Film series.
Full article: Kowalski and Skipper(Adoptive brother)
Usually when Skipper needs options, he asks Kowalski for advice. He has only defied Skipper once thus far ad he still had kept his Jiggles creation alive when Skipper was led to believe Kowalski had destroyed it. Kowalski is arguably Skipper's second in command and whenever their leader is unavailable, Kowalski usually takes over command. (An example is in "I Was A Penguin Zombie" where everyone beloved Skipper was dead and Kowalski took over temporarily until he was revealed alive in the end of the episode).
Private EditMain article: Kowalski & Private
(Adoptive brother) Out of all the penguin brothers, Kowalski and Private are extremely close. He ideally has a protective streak over Private and would hate it if any thing bad happens to his younger brother. Notably he risks everything to save Private and was visibly upset when Private appeared to be killed by the medusa serum ray but hugged Private a bit too tightly when it was revealed he was alive. In the series, usually if there is something he deems inappropriate for Private to see, Kowalski covered his eyes and also covered Private's ear whenever Skipper swears (or his angry word as he calls it.
Doris is Kowalski's love interest in the TV series. For years, Kowalski is in love with a dolphin named Doris. However, she just wants to be friends with him, giving him the friendship speech sixteen times, but he was too busy crying. Whats scary is that Doris is Dr. Blowhole's sister What's extra scary is that Kowalski has a tattoo of her on an unknown part of his body. He also uses her name as his password to his computer, according to Mort. They kiss for the first time in "The Penguin who Loved Me".
Main article: Kowalski & Eva
Eva is Kowalski's official love interest and possible girlfriend in the film series. Kowalski first fell in love with her when she saved him and his brothers from Dave's octopi.
Kowalski is good friends with Marlene. He informs Marlene of the possibility that she may be rooming with more than one otter. He also lets her use his unknown invention in "Roomies" in saving Rhonda. While she shoots sarcastic comments, Kowalski usually followed them and saw her having a shot in science.
Kowalski is jealous of Dr. Blowhole. One evidence is he claims that he's smarter than that no good dolphin while trying to shut down Blowhole's Ring of Fire. A second evidence is Kowalski also is jealous that Blowhole gets "all the good stuff".