After the hanging of the previous commander, Godry Borrell, Titus was named commander of the gold cloaks by the Hand of the King, Loren Lannister. He was given the task of hunting down the perpetrators of a raid on the goldcloak's armory.
Titus captured and tortured a suspected perpetrator, a boy named Xo. When Xo gave him the location of the rest of the thieves Titus had him killed.
The goldcloaks descended on the location (known as Sanctuary to the members of the Fleas), but most of the Fleas had fled after Xo's capture. A handful were caught and locked in gibbets until they starved to death.
It is whispered that Titus pays well for informers and seems to have much of King's Landing under his iron boot.
When Lord Ferment Redwyne attempted to poison the King and Queen at their feast, Titus was put in charge of securing information from Clement Redwyne about who was responsible for the treason. He tortured the man beneath the black cells.
"Titus the Terrible pays a pretty penny for informers, I hear." - Wat
"The Commander’s smile made Damon uneasy. Titus had been his father’s man, at Casterly Rock and King’s Landing both. Loren had always been able to wield monsters, and to great effect, too, but when he died he left his heir holding their leashes, and Damon wasn’t half so confident in his ability to handle creatures like Titus." - Blood and Whispers
"Word out in the street is, their new Commander is harder than a coffin nail." - Harry
"He relishes pain. Delights in it as others would drink, or the Gods, or a woman's touch." - Blood and Whispers