Armin's a genius child soldier who's physically weak and has low self-esteem from a world where giant mindless humanoid creatures called titans eat humans and have all but driven them to extinction. He was one of the first Travelers and has been around here for about 3 years.

Imriel is from what we call Angel France - a world where France consists of a people descended from angels and whose society is based around love. Imriel was raised as a goatherd until he was kidnapped and sold into slavery in a madman's seraglio, where human cruelty was practiced as a form of worship.

(Armin is 18, Imriel is 10.)

And I agree! I love cross canon CR, whether or not I'm familiar with the canon.