District Attorney Harry Sims first came to the Huntress' attention in her Helena Wayne identity.  He was faced with a dilemma.  Gotham City's vigilantes were beginning to get negative press, which Simms investigated.  The press, and the subsequent manipulation of Simms, was brought on by the master criminal known as the Thinker.  With his Thinking cap, he warped Sim's thinking. 
Although initially he was hesitant to ban superheroes from Gotham, even going to Helena's office to consult with her (as her father, Commissioner Bruce Wayne, had several dealings with the resident heroes over the years).  Upon not finding her, he made up his mind to outlaw their activities from Gotham, deeply entrenched in the Thinker's spell.

When Power Girl entered Sims' office, demanding he back off from his position, the Huntress intervened and convinced the angry young woman to leave his
office.  It was at this instant that Sims recognized that the Huntress and Helena were one in the same!

Hoping to eliminate Sims', who was beginning to buck his control, the Thinker "programmed him to jump out of his window.  Though saved by the two heroines, he was in no capacity to continue.  Yet a "Harry Simms" continued his fight against the "vigilantes of Gotham".  This proved to be the Thinker, creating an illusion to the press around him that he was Simms.  Tricking Power Girl into conversing with him, he soon controlled her and sent her to attack the
Huntress…who destroyed the thinking cap and vanquished his lofty ambitions.

Sims, in the subsequent weeks, struggled to come to terms with his knowledge of Helena's duel identity.  Having been attracted to her, he was riddled with
feelings of insecurity and fear for her life.  Though attempting to find solitude at an island prison, where he could collect his thoughts, instead he became
involved in the criminal Lionmane's scheme to take over the prison, which the Huntress foiled.

Harry next ran into the Joker, who injected him with "Joker toxin" that poisoned him near death.  After then being saved in hospital by a crazed escape con, he and Helena attempted to establish a relationship, even working together.  This proved unsuccessful.  He later supported her when she was discredited in the press.