Canon Background
https://awoiaf.westeros.org/index.php/Desmond_Redwyne

In-Campaign
During Robert’s Rebellion Desmond’s lord cousin Paxter Redwyne took House Redwyne’s mighty fleet to blockade Storm’s End. Desmond wanted to join the war effort but was instead appointed castellan of the Arbor, a position he takes most seriously. On one unremarkable afternoon Desmond heard word that Meatball was again impersonating Paxter in the palace’s hall. Desmond strode in to put an end to it only to discover a lordling and a maester trying their hands at espionage. Desmond would have none of it and ordered both imprisoned. The lordling escaped through a little-known cave with a common thief, killed a guard in the effort, and was caught trying to reenter the palace with another companion one day later. Desmond ordered the cave entrance to be secured and sent word to Paxter that his presence was needed at home to oversee a trial for treason and murder.

Desmond provided uncompelling testimony against Teddy and Thaddeus during their trials for treason. The maester was found innocent while the testimony of Meatball convinced Lord Paxter of Teddy’s guilt.