Raymond Z Gallun's "Stamped Caution" (novelette, first contact, free): Humans-Martians successfully make peaceful first contact
Eventually, humans make a return trip to Mars, carrying the now grown Martian with them. Some drama there, & we see the beginning of a kind of wary trust between the two sides.
Fact sheet.First published: Galaxy Science Fiction, August 1953.
Download full text from Project Gutenberg, Manybooks, Feedbooks.
Related: Stories of Raymond Z Gallun.