humanity's devourer or savior? (Male tyranid hybrid X fate grand order)

when chaldea's master decides one day to summon on a banner for fun, she accidentally summons a strange boy who is.... different. How will she control the boy who claims he's the devour of worlds? Will he consume the entire earth? Or learn to protect it? Can a monster learn to be human?

[P.S, I don't own anything here, all rights belong to the original owners of all these things in my storie. You belong to yourself]