Sivasya hridayam vishnuh, vishnoh, hridayam sivah. Siva's heart is vishnu, vishnu's heart is Siva. There is much understanding and comradiare,between,the two most powerful deities,Narayan and Mahadev. They tackle the most trivial issues of the universe, with such lan that no one can miss their concern for each other .Concern also is a shade of friendship no? They share their responsibilities like If Shiv drinks poison,at the time of samudra Madhav Vishnu becomes the tortoise,the adi kurma and bears mandar parvat. If shiv kills Jalandhar, Tripuraasur,etc, Vishnu takes avataras to kill Raavan, kams,etc. Vishnu recites Siva's thousand names siva sahasranama and Shiv gives The most powerful mantra to Paarvati in place of the thousand names of Vishnu that is Sri Rama Rama ramekin rame raame,manorame, sahasranama naama tattulyam Rama Nama varaanane. Another interesting aspect is Vishnu considers Paarvati as his sister. She is Padmanabha sahodari, Madhuraminakshi Temple sthala Puran says that Vishnu,the varadaraj has performed the marriage of minaakshi,that is parvati with sundareswar that is shiva. We recite uma sahasranama which calls her as Vishnu sahodari.So like Krishna and Arjun who are brother in laws by relation and friends by their love for each other,Shiv and Vishnu are in fact the first example of exhibiting such exemplary friendship or comradiare.