I've seen a lot about Spite joining in Lucanis's anger at Solas for imprisoning Rook, which is always a treat.
I've been thinking though of how Spite would take the blood magic/mind manipulation but specifically though. We do get that fun line at the end game about "You. Hurt. Rook."
But especially when Rook first reveals the mind control to Lucanis? Especially a romanced Lucanis?
Mages using blood magic to warp your very nature is not only a real and intense source of danger for spirits, something they maybe understand even better than mortals, it is a trauma Spite has specifically endured.
Venatori Blood mages pulled Determination unwillingly through the Fade, imprisoned it in Lucanis, and for all Spite seems set in keeping its new name, that was a major source of trauma for it.
Now Pride is somehow also a blood mage and has used Blood Magic to entrap Rook and to alter their mind enough to make them fit into the locks of the Regret Prison. Literally trying to change their sense of self.
Rook, who Spite trusts more than any other human, even Lucanis, who Lucanis loves, who Spite loves in so much as an embodiment of Spite can love, and Pride has tried to hurt them and trap them and change them the way Spite was hurt and trapped and changed. No matter how confusing mortal emotions and pains and existence are that is something Spite can understand and dread/resent.
Solas is very lucky that Rook was returned to them by the time Spite and Lucanis saw him next is all I'm saying.