as far as, Pak-Iran relations are concerned they are not fraternal and cordial once since the Islamic Revolution. the islamic bond between them existed but in front of geo political and geo strategic national interests of the two states, the islamic bond is much weaker. the issue of "the Greater Bloushistan" was one was the causes which resulted in friction between the two states. moreover, in 1990s relations also deterioate when Pakistan supported Taliban which were against Shitte Islam.
so Pakistan never saw Iran as a very friendly state but also dont consider it as a potential threat in the past but in present conditions Pakistan is in no position to handle one more hostile neighbour.