I think CP-V2. Because "A friend of mine is secretly in love with me" becomes:
"A friend of mine is secretly with me in love". Does that sound right to you?

This sentence isn't diagnostic of anything because there verb phrase is simple. It could be from a V2 language (of either sort) but also of an ordinary SVO language like English.

What happens to the order when you move "secretly" to front of the sentence? What happens when the sentence becomes a subordinate clause? Here are examples of each from a CP-SVO language, namely German.

"Ein Freund von mir ist heimlich in mich verliebt." (The order "heimlich verliebt in mich" is also possible although somewhat less common. Like your example sentence, this isn't diagnostic of V2 order.)

"Heimlich ist ein Freund von mir in mich verliebt." (V2. Cf. English "Secretly, a friend of mine is in love with me" with non-V2 SVO order.)

"Sie sagt, dass ein Freund von mir heimlich in mich verliebt ist." (V2 SOV--note how the inflected verb stays at the end, which is evidence for underlying SOV order.)

*"Sie sagt, dass heimlich ein Freund von mir in mich verliebt ist." (CP. The kind of movement allowed in main clauses isn't found in subordinate ones.)

Hmm. I'm afraid I don't really understand the difference of CP versus IP in V2. I didn't even know of such a thing until exactly four posts ago... And up until now I thought that word order in Higgish was straightforward, va.

Basically, what happens to the word order in subordinate clauses? Is it different from the word order for main clauses and, if so, how?

No, a subordinate clause has the same order as an independent one. Nietszche becomes:

Arggh.

Ŧis es an cæn yf wyrman I kena nyt.

Sorry, what is the relationship between the English quote and the Higgish one? The original Nietzsche is: Was ihn nicht umbringt, macht ihn stärker. (Word-for-word, "What him not kills[*] makes him stronger.") SOV in the dependent clause, V2 in the main one. Compare Swedish Vad som inte dödar honom, gör honom starkare. (WfW: "What that not kills him makes him stronger".) SVO, V2. In either case, negation comes immediately before the finite verb, so your version(s?) with the negative particle in clause-final position sound very odd to me.


[*] Lit. "aroundbrings".

There is NO relationship between the Nietszche and the Higgish sentence AT ALL. As a matter of fact, the sentence translates directly to:

This is a can of dragons I knew (of) not.

All I can really say at this point is that the language's grammar makes sense to me, though now I think that it is actually IP-V2.

Interesting! So it appears that Higgish either lacks relative pronouns or optionally drops them (like Modern English but unlike other Germanic languages). Unless, on second thought, the translation of the sentence is "I didn't know that this was a can of worms." In that case, Higgish drops/lacks a subordinating conjunction equivalent to English that. (Again, a feature of English not found elsewhere in Germanic as far as I know.)

No, it's more that, at least in that sentence, that kena translated to "know of", but not directly. For instance, while I know that Billy Idol exists, and know that he is a musician, I have never met him personally. Therefore, I would say "I know of Billy Idol", or in Higgish:

But in other sentences, I think that Higgish generally keeps those wonderful little relative pronouns, and does have that, in Higgish it would be ŧæt. However, note that I said "generally" on the subject of relative pronouns, which means that, while they are never dropped in "official" speech, the Higgish people are world-famous for laziness...

Right, but you still have two finite verbs in that sentence--es and kena. That means two clauses, which in turn means one must be subordinate to the other, right? Or is there a kind of loose coordination going on along with a dropped object in the second, i.e. "This is a can of dragons [and] I [of it] knew not."? (That sentence would work fine mutatis mutandis, in Osage for instance.)