Yay! So happy Dino's around! I have four characters to offer:
Eden and Fiona are his coworkers in the WES. Eden is a herbologist from America who does quite a bit of traveling and is... not quite so easygoing, but loves to have fun and is approachable but has a bit of an abrasive side. She's also a "tree-hugging" environmental activist. Fiona, on the other hand, is a very laidback Inuit cultural consultant and public speaker. She likely would be involved any time Dino entered Arctic waters in Canada to ensure his team is culturally aware.
I also have Delyse, a Caribbean mermaid who has started cooperating with the WES. She'd have some interesting things to tell him, I'm sure.
Finally, Apollo could be a potential fling if Dino ever found himself in San Francisco. He's a junior healer there and is pretty laidback and easygoing, despite coming from a high profile family. If Dino associates with Apollo, he'd likely also end up coming across his twin sister Artemis, since Apollo and Artemis share just about everything with each other.
Hope this helps!