Some headcanon on Sirzi’s deers. Here is Vernalis, who belongs to eikerren species - deer version of alicorn.
 
Vernalis was not always all wise and majestic, despite being more of a god than pony royal sisters. His purpose is to protect the world tree, and it could be done by multiple ways. When the world was yonger and mortal deers were not even imagined, the greater guardian wandered through wildernes with bow and arrows, seeking for last remnants of primordial chaos which he regarded witless and malevolent. He watched and waited before every shot and teached his weapon as it was his friend in these long journeys. They learned more and more until the hunter’s knowledge turned into respect and love. Then Vernalis abandoned his crusade and cursed his bow making it never shoot if wielded with no regret for the victim. It is now stored secretly in the prince’s palace as a reminder of the times when there was no being who did not deserve a regret.