I think Manuel is totally normal if you don’t think that the incubus took his heart but if the incubus did take his heart he would be like a zombie(plus whenever you see a raindeer it’s like his Guardian angel not him)
There’s a part when Manuel rushed to save the incubus, the deer said something along the line “you did just like your ancestor would”, and when Manuel was about to be burned down, the deer sent message through his underling to the incubus to get Manual saved.
So my theory here is that Manuel’s parents (or ancestor) saved the deer in the past though knowing he’s a devil, that’s why the deer bear a favour toward them and wanted to save him, Manuel then decided to save the incubus after regaining his concious without judging him as a devilish being, just like his parents (or ancestor) did.
And the part about the incubus (Haruko I guess) said that “even if I gave his heart to god...”, I think it’s because Manuel got his heart replaced, so his own heart has been died (sent to god)/ or after getting a new heart, the old useless heart became Haruko’s food (since he said it’s HIM that sent it to god). I think it’s a very interesting mentaphore here considering the fact Manuel no longer has his original physical heart (the leader’s son- I’ve forgot his name- also said it’s like his heart has been ripped out of his chest), he can be consider as the heartless guy, but actually is the one that has the most sympathy to every beings without judging them, while the ones with their own physical heart are in deed the heartless bastards
That’s my interpretation reading the story:)
is manuel like part raindeer or something? also im wondering if the incubus at manuels heart when he was little because in the last page he said “even if i gave his heart to god the red of him is mine”, thoughts?