"I honestly think she should have been shipped with Kayn just sayin"
no don't taint my precious shadow assassin with that trickster thot.
"P.S: Is Kayn the love child of Syndra and Zed?"
Not possible.
I'm currently doing an analysis/theory on Zed and Akali's history and their roles in the Kinkou/Order of the Shadow Timeline.
Long story short, Kayn was first and foremost born and raised in Noxus. Secondly, at the time Kayn would be born, Zed would have been a preteen/teenager. Still a part of the Kinkou. Kayn was 10 years old at the end of the Noxian/Ionian War, which ends 8 years after Zed and Shen are about to hunt down Jhin. They hunt him down for four years, and the War starts shortly after, probably within 12 months (if not a bit more) of Jhin's incarceration. Then, the Grand Stand at the Navori takes place well into the War, at least a year into it. Meaning that Irelia, who was 14 at the time, would be 17 at the end of the war, which occured three years after the Grand Stand. Then, Zed finds Kayn as a 10 year old, and takes him in. In the current day, Kayn is 17. There would be no possible way for Zed and Syndra to have produced Kayn, biologically and chronologically speaking. Moreso, we can presume that Syndra's magical power could be genetic as well, meaning Kayn would have possibly inherited it on some level. Which is not the case.