I think a formative part of incest au Jon coming to terms with his sexuality should be an all-out obsession with his dad. Over time he gets better and better at hiding it until he’s convinced he’s over it and normal now but there’s a good few years where he’s constantly thinking about and obsessing over and creeping on Elias. And it’s incredibly formative to him.
His kinks and fetishes and understanding of sex and relationships is like. Hugely informed by the fact that he spent several years wanting his dad to bend him over and fuck him soso bad. And maybe nobody would ever guess on their own but if anyone who knew him ever found out it would genuinely explain So Much for them.