While never noticed by those affected, erasing a character from history often comes with weird consequences, past modifications, and serious plot deviations.
For example, Mithras stealing Crown Prince Lysander's destiny and erasing him from history changed Gaiseric, Celestia, and Elektra's pasts, among many others, indirectly leading to the Uriah male line's slaughter by the Queen of Monsters.
As for Arian being erased by transcendent forces, that too had immediate consequences on the past and present. In this new timeline, Cassandra finds out about Luther's infidelity on the day of their marriage and never consummates the union with him—thereby making Mithras her first.
Their relationship also starts much sooner, with Mithras being spoiled rotten by Cassandra growing up while helping her to the very best of his abilities and accumulating a lot more snake monsters.
