Hello. I am on mobile and do not know how to tag for spoilers so my apologies. Also I sincerely hope /u/Devilfish45 doesn’t mind me using their format title for when they post. I think it’s great to post that way and wanted to imitate it.

In the original Eisenhorn trilogy the Inquisitor was tortured by a heretic with a neuron glove. Most of Eisenhorn’s nerves were burned out of his face and thus he could not make any facial expressions after that. In The Magos, which takes place so many years after Hereticus, something happens:

‘Why...’ said Eisenhorn. ‘Why are you being so nice to me?’ ‘Well, because, quite frankly,” said Cherubael, “and please don’t tell anyone, but right now you scare the absolute shit out of me.’ Eisenhorn smiled. ‘Hang on,’ said Cherubael. ‘I didn’t think you could do that any more.’ ‘Neither did I,’ said Eisenhorn.

Then later on in the book:

‘I think so,’ said Eisenhorn. ‘I feel stronger than I have in years. Ready to face the endgame.’ ‘Is that a good thing?’ asked Drusher. ‘Yes,” said Eisenhorn. He smiled. ‘I don’t think I’ve ever seen you smile before,” said Drusher. ‘It’s not something I’ve done in a long time,’ said Eisenhorn.

That first moment made my jaw drop. You get the mental image of the perpetually stoic Inquisitor. One that wants to smile but can’t. One doomed to a lifetime of placid expression. Then this happens. It’s not said how yet, maybe he healed? However the prospect of Eisenhorn being able to do something as simple as smiling is incredible.