Vindeliar is pale and soft-bodied, and is often said to look very young. Due to his apparent disabilities and lack of prophetic ability, he was intended to be disposed of shortly after birth, along with his twin sister Odessa. However, Dwalia rescued him and attempted to train him as a White instead.
Vindeliar is markedly strong in a magical ability that is thought to be related to the Skill. He is able to manipulate the perceptions and memories of others so that he and his companions go unnoticed and unremembered. In Assassin's Fate, it is revealed that this ability stems from Vindeliar's consumption of serpent blood.
Vindeliar accompanies Dwalia and the other Servants to Withywoods on their quest to locate and capture the Unexpected Son. During their raid, he lays a Skill-fog upon the estate that renders all of its inhabitants, save Perseverance and the Skill-sealed Shun, complacent to the violence around them. After the Servants depart with Shun and Bee, the effects of Vindeliar's Skill-fog linger, suppressing the memories of the raid.
As they travel, Vindeliar continuously enchants anyone they encounter along the way, allowing their passage to go unremarked. However, Ellik grows frustrated with Dwalia's refusal to use Vindeliar's talent to make their journey more comfortable by stealing from the helpless townsfolk. He convinces Vindeliar of his acceptance by Ellik's troops, winning him to their side by allowing him to enchant the townsfolk and steal anything he wants. Vindeliar enjoys the freedom and the loot, but becomes uncomfortable when Ellik's men begin to rape Odessa and demand that he participate. Dwalia attempts to stop their disagreement and Vindeliar's stress causes him to lash out with his magic. He causes the troops to fight and kill each other and renders Ellik invisible to his men.