Worf's son in Star Trek: The Next Generation, Alexander Rozhenko, returned in Star Trek: Deep Space Nine — but what happened to the young Klingon after? Worf is a Klingon warrior and a Starfleet officer who was raised by adoptive human parents, Sergey and Helena Rozhenko. Being a Klingon by blood but having been raised in a human environment, Worf occupies a difficult realm between two very different worlds — which makes his unexpected parental responsibilities for his part-human, part-Klingon son, Alexander, even more complicated and difficult.
Alexander was the result of a union between Worf and K'Ehleyr; the daughter of a Human mother and a Klingon father, K'Ehleyr was uniquely suited to be an Ambassador between the Federation and the Klingon Empire. Worf and K'Ehleyr became romantically involved in the TNG episode "The Emmissary," but after she rejected Worf's marriage proposal, the two parted ways. Alexander was the result of that union, and although Worf initially rejected welcoming Alexander into his life — due to the "shame" on Worf and his descendants due to him receiving a Klingon discommendation — K'Ehleyr's death left him little choice but to take responsibility for his son.
Alexander appeared several times in TNG, despite not being a series regular; however, he did not follow his father to Deep Space Nine, instead opting to live with Worf's human parents on Earth. Alexander's future was hinted at in the TNG episode "Firstborn," which featured an adult version of the character from 40 years in the future. Future Alexander, calling himself K'mtar, reveals that he travelled to the past with the intent on making his younger self a great warrior, in order to prevent Worf's murder in the future. While "Firstborn" reveals a brief summary of Alexander's life as an adult, a number of events occurred in Deep Space Nine that suggest this alternate Star Trek timeline never happened: chief among these is the Dominion War.
Worf became a series regular on Star Trek: Deep Space Nine in season 4. His son Alexander only appeared in two episodes of DS9, although he was referenced in others (like the time Worf sweetly commented to Miles O'Brien that he regretted not having seen his son as a toddler). When Alexander does appear, in the season 6 episode "Sons and Daughters," he is now an adult — Klingon's age much quicker than humans do, so even though he's only approximately 9 years old, he appears as a teenage male. The episode's plot revolves around Alexander's misguided attempts to reclaim his heritage by enlisting in the Klingon Defense Force in order to support the Klingon war against the Dominion. He is stationed on the Rotarran, on which his father is a commanding officer. Alexander repeatedly demonstrates that he lacks the "warrior" abilities Klingons value — but he tries hard, and eventually, Worf realizes his his son's brave spirit and willingness to try are virtues in their own right.
Alexander later appears in the season 6 episode "You Are Cordially Invited," in which he is asked to be the "Tawi'Yan" (or "swordbearer") at Worf and Jadzi Dax's wedding. The role is similar to being "best man" in the wedding party. The episode reveals that Alexander is still clumsy, but he informs Worf that the Klingon crew of the Rotarran has come to accept him as such, referring to him affectionately as a good luck charm. In the season 7 episode "Penumbra," Ezri Dax states that Alexander was made a weapons officer on his new assignment on the Ya'Vang and was starting to lose his clumsiness.
Although nothing in Deep Space Nine disproves the future described in TNG's "Firstborn," the path Alexander finds himself on as a young adult is unlikely to result in him becoming the same pacifist and diplomat described by K'mtar. Worf is still alive during Star Trek: Picard, but because K'mtar was vague about when the murder was to have taken place, it's currently unclear if this is proof that Alexander's future was changed as a result of him (and Worf) meeting his future self. Worf has yet to appear in Picard, although fans hope actor Michael Dorn will reprise the role for season 2. If so, it would be the perfect opportunity for Alexander to return to the franchise — perhaps on a crew serving underneath his father once more.