Legatio Ad Gaium

Accordingly, looking upon this youth to be like a thirds-man in the games, he proceeded to overthrow him, feeling no compassion, either for the fact of his having been brought up with him, or his being so nearly related to him, or for his age, but having no idea of sparing this miserable youth, doomed to an early death; his own partner in the government, his co-heir, who had formerly been expected to be all but the absolute emperor, by reason of his being the nearest relation to Tiberius; for when their fathers are dead, the grandsons are usually looked upon by their grandfathers as standing in the position of sons.