Adam Brandenburger and Barry Nalebuff’s Co-opetition (1996) added a player that most strategy maps leave out. Next to customers, suppliers and competitors sit complementors: companies whose products make customers value yours more when they have both Published. The textbook example is computer hardware and software. For a DTC brand, it’s the grinder for the coffee, the vet service for the pet food, the carrier for the baby clothes.

Why a partner beats a launch two steps out

A candidate that scores two steps out in chapter 4 usually fails on supply chain, proof or both. A complementor already has both. Partnering gives your customers the product without your needing its factory, its inventory or its credibility. It also gives you evidence. If your customers buy a partner’s product in numbers, you’ve tested the category without owning it, and you can decide later whether to build.

A partner sells you the option to launch later, for the price of a conversation now.

Forms, from lightest to heaviest

• Recommend. A page or email: what we use with our product. If the partner pays you, disclose it clearly: under the FTC’s Endorsement Guides, updated in June 2023, a paid relationship is a material connection customers must be told about Published.
• Co-market. Each brand features the other in its own emails, to its own consenting list. Don’t swap lists. Handing customer data to a partner in exchange for something of value can count as a sale of personal information under California’s privacy law, which gives customers the right to opt out Published. Have counsel review any data sharing.
• Co-branded edition. A limited product made together. It borrows both brands’ proof; set the fit questions from chapter 5 on both sides.
• Resell. You stock the partner’s product. You take on inventory, but not development. Price and bundling are covered in The First Offer.

Choosing a complementor

Score the partner’s category on the same four shared things, from your customer’s side. Then ask two more questions: do their customers look like yours, so the benefit runs both ways, and would their worst failure embarrass you? Their product sits next to your name, so the dilution research in chapter 5 applies to them too.

Test a partnership like a nudge: hold out a slice of your list and compare contribution per customer after 60 days. A partnership that only moves the partner’s revenue is a favor, not a strategy.

Do this

• List five complementors: brands whose products your customers use with yours. For every candidate category that scored two or more steps out, ask whether one of them already makes it well.
• Propose one co-marketing test with a holdout, using the partner brief in Appendix B.