𝐇𝐄𝐀𝐃𝐂𝐀𝐍𝐎𝐍: 𝐎𝐃𝐈𝐍'𝐒 𝐒𝐏𝐄𝐂𝐓𝐑𝐀𝐋 𝐒𝐓𝐄𝐄𝐃
Another custom among the Tharmr family is the taming of horses, which is rooted in the connection between Odin and his loyal steed. When the child reaches a certain age, which is normally around fourteen or fifteen, the parent takes their child to tame a horse with them since most of the horses are taken from the wild. They serve as loyal companions to the children and used in battle as well. When the new Dominant of Odin is picked, the horse is turned into an egi and in that sense, Odin's steed is an actual horse that was changed by magick. At the time, the bond between person and horse is already strong enough to connect their souls safely without causing much distress for the animal.
Barnabas did not experience this custom due to his mother's early death, which means he tamed a horse by himself. His attempt was only semi successful, however, and left permanent scars on Sleipnir's soul and changed his overall behaviour toward Barnabas and the world. While horses were always broken in a way to make them loyal, Barnabas was not gentle during the process thanks to his lacking experience and his own pain. He took a stallion from the wilds, which was Sleipnir, and broke him to create an egi from this in a quite rushed process that normally takes years.
This resulted in Sleipnir developing love and hate toward his master and creator, and caused several attempts on Barnabas' life later down the line. Remember the scar on Barnabas' chest? This was Sleipnir.
All egis are capable of turning into people if asked, or if they simply feel like it. Some prefer their human form, others prefer to stay a horse if they are not needed at the moment. In that aspect, every horse egi is different and has its own personality that is connected to their corresponding Dominant. Sleipnir usually remains a horse if Barnabas does not need him as Lord Commander, and actually despises to be a man most of the time.
Similar to Odin's overall appearance, the spectral steed varies in appearance depending on the horse's appearance. Sleipnir has always had a black coat, while his mother's horse looked different and would have looked different as a spectral steed too.
A small addition because of my Anabella's Waloed!AU ( and her in general, let's be real... ) : Barnabas is a bit particular with the custom regarding his family since he was never fully introduced to it. While it is not a custom to create a horse egi for a spouse or a loved one in general, he does anyways and created the mare Gladr, who serves as Anabella's handmaiden and messenger between her lady and Sleipnir. Additionally, he already steals a foal from the wild ( yes, he is that person ) to create a horse egi for any child he might have as a birth gift. They grow up next to his children as their companions and age at the same pace.