T-020: Ryuuzen Hasegawa

What You Character Might Know:

If they are from Rivertide, it is unlikely they would NOT have heard of the Hasegawa Water Sanctuary. It is a prominent feature in the city, and even more so since the Nera Outbreak as they take in pokemon in need and rehabilitate them. The aquarium and sanctuary is open to the public, so any characters could have come by! 

Residents of Rivertide could also have volunteered, or perhaps even worked at the sanctuary. If that is the case, they'd likely know a great deal about Ryuu as he's pretty much an open book even around mostly strangers.