|“||Human bonds are leaves in the wind. They offer you nothing.||„|
|~ to the Avatar regarding their friends|
He was first seen with a contingent of soldiers trying to assassinate exalt Emmeryn of Ylisse, but was seemingly stopped by "Marth" and was thought to have died. But, he was seen in a dark abyss talking to a humanoid version of Grima. Two years later, Validar and Aversia aided Chrom by providing him a fleet of ships to defend themselves from Walhart's troops. Later that same night, Validar was shown to have the ability to get into the avatar's mind and could control him/her.
Eventually, after Walhart's death, Validar asked that Chrom and the others would visit him at once. When they did, he demanded that they would give them the Fire Emblem or else. After taking it by force, he headed straight to the Dragon's Table to revive Grima. At the Dragon's Table, he formed a dark barrier so Chrom and the Avatar would be separated from everyone else. During the battle, Validar took control of the avatar and had him/her strike Chrom with magic. While feeling like he had the upper hand, Chrom turned out to have survived that attack and Basiello was revealed to be alive. After Validar's death, it turned out that the future cataclysm was not prevented, thanks to Grima time-traveling with Lucina.