Sand E. has no known enemies or rivals.
Warning: This page or section contains speculation that may not be accurate.
He and Sand E. are quite close and had known each other for their interests in the sea. He is very grateful to have such a girl to do his searches for him.
In What a Dive, Patch tells Sand E. that he is looking for treasure, and so Sand E. goes to extreme lengths to find the perfect treasure for him, but Patch likes the old boot she found. Nonetheless, he makes Sand E. a pirate. It's possible that they like each other.