By the time of To Ride a Rathorn, where we encounter them, Tarn and Torvo are both fifteen or sixteen years old; young for a Kendar, but a great age for a Molocar. The Falconer is sympathetic to Tarn's soon-coming loss, but Tarn is in some denial about it.
When the senior Randon go out hunting the rogue rathorn that has been bothering the horses at Tentir, Tarn begs to be allowed to take Torvo on the hunt, but is rebuffed. Later, they have their chance, when Gorbel sneaks out with his hunting pack, Caineron companions, and the RandirSimmel. Given Torvo's advancing age, they fall behind, but do independently find the young rathorn as he stands between Bel-tairi and the hounds. Torvo then expires, which triggers the young rathorn's buried memories of his mother's loss, and his scream affects everyone watching.
Gorbel later gives Tarn a Molocar pup, Torvi; he pretends that it was no big deal, that it was just a matter of giving the boy a runt that would have been killed, but Jame knows better.
↑To Ride a Rathorn, "Chapter IX: School Days", I — "That meant the hound was fifteen or sixteen years old, a great age for his breed. […] 'Well, now,' said the Falconer, not unkindly. 'You have the talent. There will be others.' 'It won't be the same!' 'No. Alas, that we should out-live so many of those whom we love.' "
↑To Ride a Rathorn, "Chapter XII: Unsheathed", I — " 'I reckon they've called up every hound in the college except Gorbel's private pack and Tarn's old Molocar,' […] 'Tarn is as mad as fire about that, […] He won't admit that old Torvo isn't up to it.' "
↑To Ride a Rathorn, "Chapter XIII: Blood and Ivory", VI
↑To Ride a Rathorn, "Chapter XX: The Bear Pit", II — " 'The Caineron Lordan gave him to me,' he explained, trying to escape its great, sloppy tongue. 'We haven't bonded yet, and of course nothing can replace Torvo—Turvie, stop that!—but still…' […] 'Runt of the litter, wasn't it? Either that or throw it to the direhounds.' "