So I found the part and frankly it kinda implies that the throne is not inherited father-son because of ppl not being happy with the choice of Zenos as heir, but then I had a worm in my head and went to read the short story and there Zenos is called Varis' Heir before his ascension as emperor.
Now unless we have to consider this a retcon of the short story, we should consider idd Zenos as his biological son, though it's interesting that in the short story Titus is said to be the Emperor's second son while Zenos is simply called ready heir.
Now this might imply just an adoption which as I just said if it's like ancient Rome it's nothing to be ashamed of, but I would ignore this eventuality since it's not clear enough.
As for Solus, I'm still of the opinion that we can't really say that whatever was written before really holds up, Perhaps a real Solus existed, perhaps not, we know for a fact that by the time he decided to create an empire Solus was already an ascian and said ascian might or might have been present during the ancient allag( what he said when comparing to allag).
