Enda O’Doherty at The Dublin Review of Books:
Colm Tóibín presents us with one account of Mann’s gradual progress away from German nationalism. It might not be the last word on what seems to have been a complex and tortured journey, but it functions well in the context of the demands of a novel, where the shifts in perspective must be presented dramatically and are often portrayed through Thomas’s interactions with others, principally members of his large and turbulent family. First and most important of these is his wife, Katia Pringsheim, who is deeply suspicious of his friendship with the nationalist (and later Nazi) writer Ernst Bertram. On the outbreak of the First World War Katia asks her husband to consider how they would feel if their two boys, Klaus and Golo, were old enough to be conscripted, “and we were waiting here each day for news of them”: “And all because of some idea.”
The doings of the Mann family provide much of the necessary human interest of The Magician. Highly gifted and highly-strung, they are a problem for Thomas from the start, but all of them, and in particular the eldest pair, Erika and Klaus, have the function, along with his brother/rival Heinrich, of slowly pulling him towards a braver, more radical opposition to Nazism.
more here.