This thread won't mean much to you if you don't care about the lore, and honestly, you're right to do so. So just feel free to ignore this boring and worthless rant by some idiot (me).
Oh, and there are also unmarked spoilers for the end of Act 1.
Alexandar is supposedly the Son of the Divine, Lucien. I've never heard of Alexandar. There have been two Divinity games set after Divine Divinity, Beyond Divinity, 20 years later, and Divinity 2, 70 years later.
This game is supposed to be about 4 years after Lucien's death*. There is at least one portrait of Alexandar in Fort Joy. It's 8 feet tall, and if you zoom in you can see the portrait in great detail
. Alexandar has a grey goatee and is bald. He looks to be about 60 years old. That would make him 10-20 years older than his father given Lucien's appearance in Divine Divinity.
For Beyond Divinity, a Novella was created, "Child of Chaos" which detailed some aspects of the childhood of Damian. There's no mention of any Alexandar, or any romantic connection in Lucien's life. At one point when Damian is an infant, Lucien specifically notes that he's never had children of his own. So to fit Alexandar in, that would make Alexander under 20 years old with the face of a 60-year old.
Alexandar is in all aspects set up to be a really important person, the top guy, the man in charge. But at the end of Act 1, he is unceremoniously killed by the protagonists in a battle. He doesn't teleport away, he falls down dead and stays there.
It's true that would make his absence from mention in Divinity 2 make more sense. It's also true that having him survive by teleporting away is a dead-horse cliche in videogames at this point. (I presume Dallis will be the new head of the Magisters chasing the party down.)
But I have to ask what the point of making Alexandar Lucien's son is supposed to be if he's just going to get killed off immediately? You might as well save yourself the headaches with the sudden appearance of a son into the canon and just call Alexandar Lucien's top general, fixing both the "wait, what son?" bits and the "wait this guy is way, WAY too old to possibly be his son" bits.