>This is the opposite of what you asked but I think it's neat: In Basque,
>all verbs might have an indirect object (marked with dative), even the
>intransitive ones! Just think about it, you can always say that you did
>something on behalf of someone, for someone, and this dative covers that.
>Why is this relevant? Because the verb agrees with the dative, whatever it
>acts as, along with the subject and object.
>|io| is Basque for have[*], present tense, agrees with a third person
>singular subject marked for ergative, a third person singular object
>marked for absolutive, -and- a third person singular indirect object or
>something, marked for dative.

The form is "dio". "d" is the absolutive 3rd person mark,
"i" is a predative particle and "o" is the dative 3rd person;
the verbal root has worn out completely and the ergative 3rd
person mark is fused/vanished (the original form might have
been something like "d-a-du-ki-o-o" 3p-pres-HAVE-predat-3p-3p).
But that's a tripersonal transitive (so-called 'nor-nori-nork'
form: "3p _has_ 3p to 3p", e.g. "Semeak bere aitari ura ematen
dio", 'The child brings his father water), the dipersonal
intransitive 'nor-nori' form is "zaio" ("3p _is_ to 3p"),
e.g. "Gizonari harria erori zaio" ("A/the stone has fallen
onto the man", lit. man-the-to stone-the* fallen it-is-to-him).

In Spanish, a dative would be used too ("_A_l hombre _LE_ ha
caído una piedra), so for us such constructions of dative
with intransitive look perfectly natural and straightforward
to translate to/from Basque.

(*) This Basque determiner does not always translate as
'the', because it is grammatically necessary in a sentence
like the above and, if you use the numeral 'one' as
indefinite article, the semantic nuance conveyed is not
the same as English 'a' ("Gizonari harri bat erori zaio"
would mean "Some stone has fallen onto the man" or
"A certain stone has fallen onto the man").