existentials are inverted universals

universal.scala

// [info] Running p.Run
// List(Fish(Bob, Esq.,12), Kitty(Thor, Esq.,java.awt.Color[r=255,g=200,b=0]))

import java.awt.Color

package p {
  trait Pet[A] {
    def name(a: A): String
    def renamed(a: A, newName: String): A
  }
  case class Fish(name: String, age: Int)
  case class Kitty(name: String, color: Color)

  object Fish {
    implicit object FishPet extends Pet[Fish] {
      def name(a: Fish) = a.name
      def renamed(a: Fish, newName: String) = a.copy(name = newName)
    }
  }
  object Kitty {
    implicit object KittyPet extends Pet[Kitty] {
      def name(a: Kitty) = a.name
      def renamed(a: Kitty, newName: String) = a.copy(name = newName)
    }
  }
  object Run {
    def main(args: Array[String]): Unit = {
      val bob     = Fish("Bob", 12)
      val thor    = Kitty("Thor", Color.ORANGE)
      val pets    = List[Parapet[_]](bob, thor)
      val renamed = pets map (x => esquire(x))

      println(renamed)
    }
  }
}

package object p {
  type Parapet[A] = ((A, Pet[A]))
  implicit def liftParapet[A: Pet](x: A): Parapet[A] = ((x, implicitly))
  def esquire[A](p: Parapet[A]): A = p._2.renamed(p._1, p._2.name(p._1) + ", Esq.")
}

@paulp, I tried to make it a bit complicated https://gist.github.com/mushtaq/dadaa80ab5ef8a8f2fad