As doomed as they are, what first drew Vincent and Roshan to each other? How did that relationship progress?
Without going into too much of the world's lore(it's extensive), Vincent is a surface dweller, While Roshan lived in the underground cities belonging to the church.
Due to having a powerful timestop theurge(Important distinction, for another post), Vincent was mistaken as The Saint of Cycles, and captured by the church during a raid for experiments.
These experiments often involved trying to force Vincent to do things he simply couldn't through mental distress(killing people in front of him in an attempt to make him reverse time, having someone use an age manipulation thaumurge to rapidly age people in order to try and force him to reverse their aging, etc), as well as torture. This was also coupled with frequent reminders that if he was "pretending" to be a saint, he was dead.
Roshan heard there was a saint brought in and was very curious, so he had snuck into the facility during one of these experiments, witnessing Vincent fail once again and be beaten for it.
Realizing what they were doing to him, Roshan broke him out and they escaped to the surface together.
At first Vincent was weary of him, but as they spent a month navigating around the surface and avoiding the Paladins who came looking for them, He eventually warmed up a lot to Roshan and fell very deeply in love.
Roshan for his part took longer to come around, not only was he training to be a priest which required celibacy, but the idea of being in a relationship with another man had been hammered into his head as something inherently sinful and wrong, and it generally took him a few extra months to get over the various complications his upbringing caused in how he handled romance and sexuality.
By the time they arrived at what would become their home in northern Croix, though, they were both deeply in love and couldn't imagine a life without eachother. Vincent taught Roshan a lot about surviving on the surface, while Roshan taught Vincent how to read.
This wasn't without their occassional hurdle though. Vincent could be evasive and reluctant to show pain and vulnerability, and was also very protective over Roshan. Being from the surface, he was intimately aware that a lot of seemingly safe or innocuous things could get you killed(sanctums, random people wandering the woods, even discarded objects. and that's not even going into husks and the other various freaky monsters that reside out in the wilds, as well as the church)
He was also aware that Roshan didn't these dangers as well as he did, having grown up very sheltered in the church and only being told the surface was dangerous without any real experience of the danger and what it looked like. He also couldn't really fight and only knew how to use a revolver that, at least when they were on the surface, had very limited ammo.(Surface dwellers don't really do guns)
So, he was very helicopter-y, and it did lead to a few fights with Roshan, including the one that led to his death.