From A Wiki of Ice and Fire
|Alias||Ser Hugh of the Vale|
|Died||In 298 AL, at King's Landing|
|Book(s)||A Game of Thrones|
He is very young. He has rough-hewn features and does not look handsome.
A Game of Thrones
When Eddard Stark complains to Petyr Baelish that his investigation into Jon Arryn's death is hindered by the fact that Lysa Arryn took most of her household back to the Vale, Littlefinger tells him that, among others, Lord Arryn's squire is still in King's Landing, a newly knighted "boy" called Ser Hugh of the Vale. Eddard considers him a promising witness, as squires often know a lot about their masters' comings and goings, and announces that he is going to question Ser Hugh. This prompts a warning by Littlefinger that Eddard should proceed carefully with this, as spies of Varys and Queen Cersei are watching him closely. Littlefinger advises Eddard to send someone he trusts to question Ser Hugh, rather than go himself.
When Eddard sends Jory Cassel to Ser Hugh, the newly made knight is brusque and arrogant, stating that he would be pleased to receive the Hand, if he wants to talk with him, but he wouldn't be questioned by a mere captain of guards, even if he was ten years older and a hundred times the swordsman.
He takes part in the Tourney of the Hand, wearing armor that he has had forged for the occasion. Ser Hugh goes up against Ser Gregor Clegane. Ser Gregor's lance rides up and drives through Ser Hugh's throat, killing him instantly. Ser Barristan Selmy stands vigil for him in lack of others being close to the dead. Ser Barristan tells Eddard Stark that, as squire, Hugh desperately wanted to be knighted, but was probably not ready for it. The death by the hand of a Lannister bannerman makes Eddard wonder whether Ser Hugh has died because of his attempt to question him, but he doubts that he will ever find out the truth. Eddard feels guilty, thinking about the mother who will be told that her son died at a tourney to honor the Hand. Ser Barristan tells Eddard that Ser Hugh had his armor, worth a fair piece of silver, forged for the occasion and that he might not have paid the whole price to the smith yet. Eddard orders that the armor is sent along with the remains to the mother in the Vale and announces that he will take care of the smith.
In a conversation with Eddard, Varys mentions Hugh as a possible suspect for poisoning Jon Arryn. Varys is pointing out that, although he owed everything to Lord Arryn, he did not return to the Vale when Lysa Arryn fled with her household there, instead remaining in King's Landing and rising to knighthood.
A Clash of Kings
When Tyrion Lannister questions Grand Maester Pycelle about his role in the death of Jon Arryn, Pycelle denies it was him who poisoned the Hand, although he admits that he withheld care from him, as he knew that Queen Cersei wanted Jon Arryn dead. Pycelle believes Varys' version that it was Hugh who slipped the poison to Jon Arryn and supects that he acted on Cersei's orders.