Melvin Potter was an inventor, forced by Wilson Fisk to make him protective suits. No one was supposed to be in Melvin's shop, unless Fisk brought them. If Melvin betrayed him, Fisk would go after his friend, Betsy.
Seeking the maker of Fisk's suits, Matthew Murdock had Turk Barrett point him to Melvin's shop. Potter attacked Murdock, and briefly had the advantage due to an open wound Murdock was suffering from, but Murdock rallied and overpowered him. Potter then told him about Betsy, and the vigilante responded that he might be able to stop Fisk from hurting anyone else, including Betsy, with Melvin's help. Melvin agreed to make him a new suit and the vigilante asked him to make a symbol.
Melvin started working on a body armor that could offered protection with out giving away speed and agility, also adding small Devil horns to the mask. When Murdock returned for the hastily constructed product, Melvin asked him to protect Betsy. Murdock responded that he would keep his promise, and then Melvin gave him the suit and a pair of batons.
Inventor: Melvin Potter is a genius inventor, typically employed to create protective garments that offer a high degree of protection without trading away flexibility or functionality. He has also constructed personal weapons and equipment as needed.