How do you get a lost soul as a pet on wizard101?

To get a Lost Soul as a pet in Wizard101, you need to defeat Lost Souls in the game, particularly in areas like the Haunted Cave in the Wizard City. Once you defeat them, they have a chance to drop a "Lost Soul" pet egg. You can then hatch this egg in the Pet Pavilion to obtain your Lost Soul pet. Be patient, as the drop rate can be low, so you may need to defeat several Lost Souls before getting an egg.