In what sense is the body of Christ Christ's complement?
The body of Christ is Christ's complement in the same sense Eve completed Adam: it is the counterpart that completes Him in relationship. Christ is still waiting for and looking for this complement, and when it is suddenly filled and the last one is brought in, He will take it to Himself.
Les explains that just as Eve was the complement that completed Adam in that relationship, so the body of Christ is that complement of which Christ is still waiting for and looking for. When it is suddenly filled and the last one is brought in, He is going to take it to Himself. He connects this to Revelation 19, where the marriage of the Lamb has come and the bride has made herself ready, arrayed in fine linen, clean and white, which is the righteousness or positional aspect of the saints.