Friendship and mutual understanding are also common themes. Naruto, being the friendly and determined character he is, tries to befriend Teresa. Teresa, who has her own backstory and personality, gradually warms up to Naruto. This development of their relationship, from strangers to comrades or even friends, is often explored in these fanfictions. Additionally, the theme of fighting against a common enemy. Whether it's a powerful Yoma or some other threat that endangers both the Naruto and Claymore universes, they join forces to combat it.
A lesser - known but quite engaging one is 'Teresa and Naruto: A New Alliance'. In this, Teresa is initially skeptical of Naruto but as they get to know each other, they realize they can achieve great things together. The fic is well - written, with detailed descriptions of the two different worlds and how the characters bridge the gap between them.
The characters can be integrated by having them meet in a crossover world. For example, Naruto characters could be transported to the Claymore world and vice versa. They could then exchange their fighting techniques. Naruto characters could teach the Claymores about chakra control, while Claymores could show Naruto characters how to use their yoki - enhanced weapons.