He had been loyal to the emperor all his life, but in the end he was accused of treason, and was used as a pawn by those who swore loyalty to him, and was left to die in the wilderness. This is his destiny, and he accepts it.
When I woke up, it was a completely unknown world. Meeting him may be a new beginning. He is willing to trust him again, hand over his sincerity, accompany him, and protect him throughout his life.
The sinister and gentle prince attacks and travels through time, and the loyal dog endures it.