Lord Shiva is the one who has a team of his devouted players , performing the task of contolling the universe , and the most important ones amongst these are Nandi, Bhringi, Virabhadra and Chandesvara. Each one of them has an important role to play in the performing of assigned duties as per the wishes of the Lord , and in most temples where the Lord is worshipped you will find them to be also present . Let's see what each one of them is doing in the retinue of deities of Lord Shiva !
Worshippers of Lord Shiva hold Nandi the bull in reverence , and you will usually find him seated in front of the image of Lord Shiva in most of the temples , gazing at the Lord all of the time . Nandi is the vehicle of the Lord , and he is also worshipped by the devoutees first before they actually worship the Lord . In most cases his image is found at the entrance to the temple of Lord Shiva .
Here, the saying goes that no one is supposed to pay homage to the Lord without first paying homage to Nandi . In doing so they are to look at the image of Lord Shiva in the temple from afar , from the space between the ears and the top of Nandi's head . In fact , in India there are several temples purely dedicated to the worship of Nandi . A classic example is the Nandiswara temple in Karnataka .
Nandi symbolises the animal qualities in man which Lord Shiva rides so as to transform with his own energies . Nandi is supposed to have all the sciptural and spiritual knowledge as well as the knowledge of devoution to Hanumnaji. Interestingly enough , in several parts of India , it is a tradition to let a bull roam freely in each of the villages , so as to inseminate the various cows , as a special mark of respect to Nandi.
To begin with , Bhringi was actually a demon named Andhaka , and by the powers and grace of Lord Shiva he was transformed into an ardent and most loyal devoutee , and admitted into the armies of the Lord , as it's leader . And to say the very least about Bhringi's devoution to Lord Shiva , he would not offer his worship to anyone except for and exclusively for Lord Shiva . So much so that he would not even offer his worship to Godess Parvati !
The saying goes that once when Bhringi found the Lord in his half masculine and half feminine form in fusion with Godess Parvati , he tried to offer his worship to the Lord , and the Lord alone , by trying to enter the masculine side of Lord Shiva's form ( Ardhanariswara form ) by assuming the form of a bee. This one sided devoution of Bhringi was bound to annoy the Godess Parvati ! Soon enough , Lord Shiva made his devoutee realise the folly of his ways , and thereafter there was a change in his behaviour.
Here we have Lord Shiva in his most violent and ferocious mood , and he manifested himself in this form when he found that his wife Sati was being disgraced and insulted by her own father in front of a large public gathering . And unable to bear up to the humiliation by her own father , Sati went on to immolate herself ! Lord Shiva's anger had no boundaries , and he went to Daksha's place along with his huge armies , and beheaded him there and then itself . This is the angry and destructive form of Lord Shiva wherein he is shown wearing a garland of skulls , and with his four arms holding different weapons . Virbhadra is essentially a warrior God , having been worshipped in ancient and medieval times .
A ferocious God willing to do battle for a noble and divine cause, being worshipped by the devoutees prior to their offering obeisance to Lord Shiva in the various Shiva temples. This is a form of Chandi in it's human aspect and signifies the relationship between Chandi or Durga Mata and Lord Shiva !