She develops a friendship with Penelope in Marron's Autumn Festival when Penelope helps her pick herself back up and lays down sandbags (to stop a river overflowing) using Fukusuke. She seems to understand what Penelope is saying. They are also of similar height (very short), which is unique to most of the other Ham-Hams.
Marron is often called Chestnut because her Japanese name literally means "small chestnut", but since she was called Marron in Hamtaro: Rainbow Rescue (video game), that is her official English name. Marron means "chestnut brown" in Spanish and French.
In Italian her name is Castagnina, a portmanteau of the word castagna (chestnut) and the name Nina.