Origin

Star Trek Canon Special Note
Not everything listed in the origin is Canon.  That is because only television shows and movies are considered canon for Star Trek.  This being a comic website there are many things here that are not canon.  So unless it is contradicted in film it should be listed as part of the character biography.  
 
The son of Lieutenant Worf and  Ambassador K'Ehleyr, Alexander is 3/4 Klingon and 1/4 human.  For the first few years of his life, he never knew his father, or even that he had one, as K'Ehleyr never told Worf he had a child.  She did this knowing that Worf would insist on marriage and she had no interest in changing how she lived her life for a man.  

Creation

Alexander was created for the television show Star Trek: The Next Generation.

Character Evolution

Alexander met his father when K'Ehleyr's job required her to return to the U.S.S. Enterprise D a few years later to guide Jean-Luc Picard in arbitrating  the selection of a new C hancellor for the Klingon Empire. His mother was killed by Duras and he watched as she died in Worf's arms.  Feeling inadequate to raise his son, Worf sent Alexander to Earth to be raised by his parents Helena and Sergey Rozhenko after K'Ehleyn's death. 
 
One year later, Helena brought Alexander back to Worf. He'd had problems adjusting and was causing trouble, and Mrs. Rozhenko felt that his father's influence would help. However, the young Klingon resisted. Following in his mother's footsteps, Alexander swore off all things Klingon from an early age. Despite Worf's best efforts, he had no idea how to raise a child and he and Alexander kept butting heads.  Perhaps because of this, he ended up bonding even closer with Deanna Troi.  This relationship between Worf and Troi became romantic for a time.
 

Somewhere along the line though, they must have had more problems, because Alexander ends up some years later serving on board the  Klingon ship Rotarran under General Martok, claiming to belong to no family or house. When Worf confronts him, Alexander reveals that he felt Worf abandoned him by sending him back to Earth (although why or when has never been disclosed). After a while, serving on board the Rotarran again, they make up and seem to get along. Alexander ended up joining the  House of Martok  and acted as Worf's Tawi'Yan (swordbearer) in his marrage to Jadzia.