He was a little shorter than average, with long, brown hair that stuck out from his head at odd angles. He wore a set of worn wizard's robes and had an air of enthusiasm about him that somehow managed to be unnerving.
One of Harkle's accident-free successful spells was his Fog of Fate, which transported the caster wherever they needed to be to accomplish their goals. Upon casting of the spell, Harkle ended up in the middle of the Sea of Swords, but was saved by Drizzt and the crew of the Sea Sprite. While under the effects of the spell, he magically transported the Sea Sprite and crew to Carradoon. As a drawback of the spell, Harkle had his memory of the previous adventure with Drizzt erased from his mind.
When the Companions of the Hall entered Longsaddle in 1356 DR, Harkle was one of the first Harpells to greet the heroes. Over the following years, Harkle traveled more than most of his family members, such as visiting Mithral Hall and helping to defend it against the drow invasion in 1358 DR. He even journeyed the Sword Coast with Drizzt Do'Urden and Catti-brie in 1364 DR.