Dear Professor TR:

You wrote:
> I have a syntax question:
>
> What is the function of the group of words “that it will be perfect” in
> the sentence below?
>
> There is a danger that it will be perfect.
>
> To me it seems to work like an object predicative (complement), but danger
> is not an object here. I cannot work it out.
>
> Appreciate your help.
>
If I understand your question correctly that is an adjective clause modifying “danger.” It is not an object complement for two reasons: (1) there is no direct object and (2) it is not renaming the predicate.

> Dear JB,
> I appreciate you quick response, however, with all due respect, I tend to
> disagree with the analysis of the clause you provided.
> It cannot be an adjective clause, as there is a subject: “it”.
>
> Following the reasoning that, following an adjective clause, the relative
> pronoun will represent either the subject or the object [of the adjective
> clause], it does not make sense.
>
> If we insert the relative pronoun “that”…
>
> e.g. There is a danger that it will be perfect
>
> …we see that it [the relative pronoun] serves neither as a subject nor
> as
> an object. Is it possible that this is a complement of the noun, however,
> not an adjective clause? Something like a free complement?

The relative pronoun does not have to be a subject or object of the clause it introduces. It does introduce a subordinate clause and in this sentence that subordinate clause functions as a modifier of “danger.” You are correct that you could drop the “that,” we often do in English. But that does not change the clause’s function. Perhaps you could argue that the subordinate clause is a noun clause functioning as an appositive, but then you would have to change the verb: “There is a danger: It might be perfect.”

I would still go with the adjective clause. It does describe the noun “danger.”