Responses
Not just bc of that, it wasn’t stated here but in the novel he unlike his sister after their mentor's death still chose to trust the humans bc of giovanni but suffered betrayal one after another, so his hatred against humans besides gio is completely valid
Iser is probably reacting hostile with Yoo Seong-woon because of how humans treated Giovanni in the past. So when Seong-woo thought "its not like your protecting a chick" its exactly what Iser is doing.