From the XOR 1 WIP thread by me actually:
I had one game where my helot MC had raided House de Merre causing Horion to not reveal anything worth befriending him over. So my MC held Horion hostage and sent Linos off to deliver the ransom. When it became clear that no ransom would be forthcoming, my MC chose the option to release Horion. I never heard the fate of either of them again that game. If they are supposed to die at that point, the text never showed up for that playthrough.
and by @Havenstone:
Breden can come to the end of the game alive (and your companion for the next chapter, if you choose – like Kalt, Suzane, or Ciels). The only set-in-stone death in this game is (I think) your father’s. As pointed out above by @Norilinde, even Horion can make it to the end of the game without a death notice, with the right timing of his kidnapping and release.