He said: “Siegfried is an enormously stubborn person, and quite childish at times.
“Not to get too psychological on it, but and the idea that he’s now got to be a father to Tristan (when he isn’t Tristan’s dad, he’s his brother) irritates him.
“Partly because Tristan’s having quite a lot of fun at Siegfried’s expense at college – and not passing his exams – and partly because Siegfried didn’t get to do enough of that when he was Tristan’s age, because he was busy looking after Tristan.
“Also because James and Tris are this… it’s not a bromance, but they’re great friends, and they’re younger, and Siegfried slightly resents it.
Because he feels like a bit of a stick-in-the-mud, and he’s a widower. There are all sorts of things that make Tris seem footloose and fancy free, and that’s enormously annoying.”