Shell (also known as The Merchant) is an NPC in Infinity Blade III. She is first introduced in Siris's Act 1. When Siris opens a treasure chest in Larioth, Shell appears and beats him to it, taking a Firebrand from the chest and walking away. After Act I, she appears again as a merchant, offering to trade with Siris and Isa. She ironically will be selling the item that she stole from Siris in Act 1. Isa asks her how they could trust her, and Shell simply states that, "Paying customers are more useful to [her] than dead ones."
She sells wares that could be normally obtained through the store, except at a discounted price. Mastered pieces of equipment can also be sold at 3/8 of their original purchase price. Unlike other NPCs that do business with Siris and Isa, Shell cannot be recruited and will not stay at the Hideout permanently. Shell travels around her sail boat and comes at a random, albeit on a fairly common basis. The Merchant leaves when the player disembarks from her boat (of course this is after they accept the fact that she may not have the same items again) or leave the hideout, to start an Act or a side quest.
Her discounts are increased by Siris' Discount Card skill. Shell visits the Hideout more often with Siris' Merchant Speed skill. The merchant's wares are influenced by Isa's Rare Merchant skill, which increases the rarity of the wares. The Merchant Cargo skill causes Shell to offer more items for sale, at any given time.