The Imperial Knights from Tales of Vesperia have under their control, a bunch of "War dogs" that help them in combat. Lambert, and is son Repede, are both some of those dogs. Nylen is Lambert's caretaker much as Yuri is to Repede. Lambert is a good father to Repede and it shows after Lambert is gone. Repede comes running out to greet Yuri but then realizes that Lambert isn't with him.
 Lambert's fate
Creatures presumably made of aer attack the village that Yuri and many other knights are currently holding. Yuri and the other knights fend them off but Lambert and several other war dogs chase the creatures into the forest. Yuri chases after them only to find that the monsters had absorbed and taken over the dogs. Yuri has no choice but to kill them to protect his companions.