Do I really have to explain this, and find the most gender neutral and logically sterilized way to say it? Are you kidding me? It feels like you're giving us a hard time on purpose. No matter what I say there's going to be room for some stigmatized role to come into play as long as you're looking for them.
None the less. I will use sea life as a sufficiently alien example to get past these useless connotations.
Look at the Goby and Pistol Shrimp relationship. They are two different species that naturally pair up for mutual benefit, and they don't give a crap about constructed roles - they do it because it's effective.
The pistol shrimp is a fierce and strong predator, lighting fast. It's claws literally move like bullets. But, it cannot see well. The Goby is just a peaceful fish, easily eaten - it could be snatched up like nothing by a pistol shrimp. But, the Goby has very good eyes and senses. So, what actually happens is for some reason, the Goby and Pistol Shrimp form pairs. The pistol shrimp digs a house in coral for the Goby to live in, and protects the Goby, while the Goby uses its senses to watch out for predators and warn the pistol shrimp of danger. The pistol shrimp protects the Goby because the Goby is a compliment, and vice versa.