I do believe that while not with everything he did: Deglan canonically being originally born and raised in Skellige, before he was brought into the Wolf school, does provide a good deal of insight into how he turned out.
Considering culturally, a lot of them consider dying in a fight a good thing. A very good death falling to a monster would be, as opposed to starving or wasting away to some disease. As well as there’s the culturally common mindsight of “my clan is important and must be defended, plough the rest”.
I do think a good measure of those sorts of beliefs stuck with him as a child - and ended up being further influenced by his experiences with his school and then after becoming a Witcher.












