I know it was in the past and she was just a kid, but... ICHIKA YOU SNAKE!!!
Also, Maruo (I don't remember his name) is a pretty decent guy. He went out searching for Yotsuba and even took the girls in after their mother died despite having no real obligation to do so. He doesn't have many "parent-like" qualities, but you can't say he doesn't at least care about the quints.
P.S. Give Yotsuba her happy ending, you coward.