Blood Brother

Though Snow Elves cannot have brothers as Elven maidens physically cannot have more than one son. it is not uncommon to see close friends form a bond. Usually there is a piece of jewellery or accessory that they both wear as a sign of respect and solidarity for their brotherhood.
The most notable brotherhood amongst the Snow Elves was Andris and Damani who were already raised as adopted siblings. Amadeus served Maester Damani as his right hand man.