Many languages associate the
t sound with the second person and the
s with the third. For example Spanish (tu/tuyo, su/suyo), French (tu,ton/ta/tes,son/sa/ses), Italian (tu,tuo/tua/tuoi,suo/sua/suoi) etc. Even English associates t with the second person (thy,thine etc). German does not seem to have t for the second person (though it has d which is close) but does have third person adjectives beginning with s (sein/seine).
Modern (and I would guess Ancient as well) Greek, however has the inverse.
The second person is associated with the
s sound and the third with
t. Σου, pronounced su just like in Spanish means your(s) and του, again pronounced exactly like the Spanish tu, means his. I can imagine that του may have originated from the word for self (ἑαυτού/τον/τος) but, in that case, why the third person?
So, my question is about the history and origin of this association between
t and the third and second person respectively. Is it a characteristic of Proto-Indo-European and, if so, what happened to Greek? Did PIE have such adjectives and, if so, did they also start with
s? Any extra historical information on the origin and phylogeny of these possessives would also be very welcome.