Complex sentence: Thanos sought contact with Earth's heroes and assisted them in their assault on Paradise Omega and recruited the Silver Surfer, who had been one of the Goddess' followers, but turned against her when he noticed that he was being manipulated.
Split into simpler sentences: Thanos sought contact with Earth's heroes and assisted them in their assault on Paradise Omega. He also recruited the Silver Surfer, who had been one of the Goddess' followers, but turned against her when he noticed that he was being manipulated.