Vespasian seemed to play a bit of the favorites game, openly preferring Titus (and, tbf, Titus had accompanied him across the whole of the damn Empire, literally saving his life in Britannia and acting as his lieutenant in Iudea, while Domitian was still a child in Rome), so he would probably be disappointed but not surprised that the unfavorite son continued proving himself unworthy.

Titus, who went far out of his way to be kind to his little brother and include him even while their father was alive, probably would have mused that his kindness was wasted - especially since it's suspected by some contemporaries that Domitian was the one who poisoned Titus (or ordered it).