Heidel is a middle aged, noble-looking man with pronounced facial hair, sporting bushy eyebrows, side-burns and a curled moustache. He wears a violet business suit from his pants to his matching sleeve coat, with black hemmed front bucket to collar, cloth shoulder pads, with yellow lining to buttons. He wears a dark emerald vest shirt underneath the suit, followed by a white collar shirt underneath it, a pink tied neck bow with a broach emerald gem dangling from it, and brown shoes.
Heidel is a haughty person with a lot of money and connections, who enjoys using his position as a noble to do whatever he wants to. Though seemingly a busy man, he throws extravagant parties on a regular basis. He is cowardly, relying on his brother's reputation and power as a noble, and is not afraid to endanger others should he see it as an advantage to himself.
He seems to enjoy doing things that pleases him despite the morality of them, even to take comfort within the Reinford Family’s home when they are not in charge. He can be sly and conniving, thinking that his niece Angelica and and older brother Gerhart limit their own potential through their wretched, worthless sense of pride. He seems to have little caring when even endangering his own niece while making an excuse for his brother to believe. But when things don’t go his way, he begins to panic under the situation while trying to regain control of it.
Prior to the October War, Heidel was the director of Reinford Group's 1st Factory.
During the October War, the Noble Alliance seized control of the Reinford Group, giving him the Eisengraf. Heidel took advantage of the chaos by hiring Nidhoggr jaegers to kidnap Irina Reinford and kept her hostage onboard the train, keeping her as far away as possible from him. He then occupied the building's twenty-fourth floor, which is where the Reinfords made their residence. Publicly, he claims that Irina has fallen ill and states that he will temporarily assume her position as acting chairman until she recovers.
As acting chairman and member of the Noble Alliance, Heidel shut down half of the group's divisions, forcing the other half to make weapons and Soldats for the war, doing the same with other businesses in the city. With these changes, share prices dropped, the group stopped exporting, and the city started receiving fewer tourists and trade, making the citizens unhappy.
After Rean, Alisa, Angelica and the others rescue Irina, they go after Heidel to take the company back and arrest him for his actions. Heidel panics as the Nidhoggr jaegers are unable to apprehend Irina and Sharon, so he opts to unleash swarms of archaisms in the building, disregarding the safety of his employees. When confronted, he deployed Regenenkopf Type-0 and four Shigure archaisms, although they were destroyed in the ensuing battle. Irina then arrived, commending him for his slyness, but condemned his arrogance for using her home as his, promptly incapitating him in a few blows. When Gerhart declared his neutrality in the ongoing war, he takes a leave of absence from his role as Director in the group, and is confined to his mansion for his crimes.
Following the circumstances with the Great Twilight and appearance of Salt Pale-like objects, Gerhart left Heidel in control of Nortia while he was coordinating the war effort for the nobles. Heidel kept watch over the province in his brother's stead, both aware of the situation the country was in and the threats that Gerhart would honor if he stepped out of line.
- Crome mentions Heidel owns the title of count, and is Gerhart's younger brother.