Translation:I thought there had been something special.
No one says "Eu pensei que tinha havido algo especial". It's too formal. Usually says "Eu pensei que fosse algo especial" or "Pensei que houve algo (de) especial"
While it is a strange (and philosophical) sentence, I think my answer "I thought I had been something special" should have been accepted, since past imperfect for eu and ele/ela are the same! Anybody concur?
I'd concur for other verbs. But "haver" cannot do this.
Only a few specific cases can take "haver" with a subject.
Your sentence: "Eu pensei que (eu) tinha sido algo especial"
Even so, it's really not good to omit that eu. This sentence has many possible meanings with other persons, being "it" probably the first thing to come up in mind instead of "I".
Every sentence in this section is unnatural English... anyone who is not a native English speaker please ignore this section... nobody talks like this.
It's grammatically correct but utterly devoid of any meaning. I can't imagine ever using it.
To happen is an action. To be is to exist.
Eu pensei que tinha acontecido algo especial (happened)
Even being a Brazilian i'm not sure about that, but I believe isn't wrong, but Iwould change the 'Quite' on Danmoller coment into a 'Very' to the Weird.
Suggested Improvement: I thought there had been something special (between us). Very clear in English! Eu pensei que tenha havido algo especial (entre nós). Portuguese é correcto? Native English speaker....
If the verb were "tinha", corretíssimo. (fixed comment, thanks emeyr)
In fact, that's exactly the first thing I thought when reading the sentence.
Daniel: re: raf_iggy's use of present perfect subjunctive (tenha havido). Can it be used after the main verb is in the preterit? I thought that it had to be introduced by a verb in the present tense. Confused!
Mistake of mine. It must be "tinha".
"Eu pensei que tinha havido algo especial (entre nós)".
Can someone explain where the there is in the portuguese or what I should think of as there here.
Thanks think the suggestion confused me when trying to answer. Also have been trying to revise my Italian.