I'm reading Bloodline by F. Paul Wilson and came across the following snippet:
Jack needed to read this. He'd have loved to take it home to pore
over, but Bolton would know he'd been invaded when he found it
The narration goes when Jack snuck into Bolton's room and now he's looking at the book.
Why does the author uses the perfect tense after the modal verb? This way it seems that Jack doesn't want to take it home right now looking at it but wanted to do that in the past
Modals followed by auxiliary have are almost always irrealis (counterfactual) conditionals.
He would love to would be realis: there was a possibility that he might yet take it home. He would have loved to means that he did not take it home - that possibility was not realized.
I don't agree with WS2 that there is anything sloppy about He would have loved to take it home. To have taken it home is of course possible, but English speakers often omit that sort of complexity when the temporal relationships are clear.
The reason seems simpler than the other answers to me: the narrator is describing past events. Jack needed (in the past, from the narrator's perspective) to read this, and (at that time) would have loved to ...
Jack needs to read this. He'd love to take it home to pore over ...
would also be perfectly acceptable, but that is not normally how fiction is written.
You are quite right. It is sloppy English in my view.
I think we can assunme that "He'd have loved" is short for "He would have loved". That part is not a problem.
But the whole sentence should read He'd have loved to have taken it home to pore over...
But relevant to this answer is my comment to @FumbleFingers below. I will concede that if the book is written in the present tense, or what has sometimes been described on ELU as "the historical present" - like Carlyle's French Revolution (unlikely) - then it is correctly worded.