THE ILLUMINATI IN INQUISITOR

[Raghnall]

Been a looooooong time  since I read Eisenhorn, but IIRC, the Arbites (can't remember his name) who serves him betrays him at the end of the series, and gets possessed by Eisenhorn's bound daemon  (also can't remember his name; Cherubael, maybe?) and the resulting monstrosity now likes Eisenhorn, rather than wanting to screw him over at every possibility. 

If I do recall that correctly, that would seem to indicate that something of the underlying man survived.

I don't think that's a particularly good example to use really, given that Fischig was shot to death first, and then Cherubael was bound to his corpse. Cherubael was undoubtedly more obedient afterwards, but that's probably because of the tighter bindings restricting a lot of his power.

A better example is probably when Aemos absorbed Cherubael while they could prepare the proper bindings, but that killed him very quickly.

[Inquisitor Thaken]

Been a looooooong time  since I read Eisenhorn, but IIRC, the Arbites (can't remember his name) who serves him betrays him at the end of the series, and gets possessed by Eisenhorn's bound daemon  (also can't remember his name; Cherubael, maybe?) and the resulting monstrosity now likes Eisenhorn, rather than wanting to screw him over at every possibility. 

If I do recall that correctly, that would seem to indicate that something of the underlying man survived.

I don't think that's a particularly good example to use really, given that Fischig was shot to death first, and then Cherubael was bound to his corpse. Cherubael was undoubtedly more obedient afterwards, but that's probably because of the tighter bindings restricting a lot of his power.

A better example is probably when Aemos absorbed Cherubael while they could prepare the proper bindings, but that killed him very quickly.

And yet the resulting being's (Fischig-Cherubael) personality saves Eisenhorn's life when it doesn't have to. 

[MarcoSkoll]

While I'm not generally a big fan of Dan Abnett's writing, Cherubael seemed in character for a daemon.

No, Cherubael didn't have to save Eisenhorn... but daemons are timeless, and what they do might not make sense now, but may slot into some plan that they've yet to even think of. Besides, I think Cherubael did actually like Eisenhorn, despite constantly interfering - that kind of arrogance is very suited to daemons, with them looking on others as both admirable and inferior at the same time.

Obviously, he/it was angry when imprisoned and vengeful when released - but that sort of makes sense. Daemons are creatures of emotion (literally), so I'm sure they could easily get caught up in a moment rather than their long term plans. (People certainly can).

It's probably open to interpretation, but it's certainly not proof positive that the personality of the host can affect the daemon.

[Inquisitor Thaken]

I think he was fairly clear that the daemon's personality changed after the arbites' death.  But, as you say, open to interpretation.

[Drubbels]

Eisenhorn (the omnibus), p 751

I had been much more careful in my design of this daemonhost. Elaborating on the basic and hasty ritual construction Aemos and I had wrought in those last few minutes aboard the Essene, I had supplemented the wards and rune markings on its flesh to reinforce its obedience. This daemonhost would not be permitted to have any of the capricious guile of the previous versions. It would not rebel. It would not be a maverick that had to be watched at all times. It was bound and locked with triple wards, totally subservient. [...]

The text goes into detail on the nature of the bindings, but never connects it to Fischig's influence.