The most interesting part about analyzing the play Trifles is actually awarding the characters the importance that they deserve as part of a complex plot.
This being said, it is clear that, aside from Minnie Wright, the other two central and most important characters are Mrs. Hale and Mrs. Peters.
Minnie Foster Wright is a presumably a middle-aged woman by the time that she is found, dumbfounded and in shock, at her house after having told a fellow farmer that her husband, John Wright, laid dead in their bedroom. Her first appearance is taciturn, and "all done up", in the words of Mr. Hale. This shows that she looked disheveled and utterly stressed out. We know by Mrs. Hale that Minnie was once "fluttery", "pretty", and used to wear pretty clothes "with ribbons" but that this is no longer the case. Minnie is now tired, much older, ungraceful, and perhaps even untidy-looking, considering the state of the house, and of her mind.
Mrs. Hale, who is the most clever of every character in the play, is observant, analytical and quick to make connections. As a fellow farm wife of Minnie's,she is aware of the amount of work that comes with the lifestyle. Being close to Minnie's age, we can also consider her a middle-aged wife, humble-looking, but wonderfully seasoned by the experiences of the daily toil. It is Mrs. Hale who can make the deeper connection to Minnie, subtlety pointing out that "men's hands are not always as clean as they ought to be", and defending Minnie from the silly remarks of the country attorney and the sheriff. Mrs. Hale is, above all, remorseful for not being able to tend to Minnie when she needed someone the most. This is what ultimately leads her to suggest the suppression of the evidence from the men.
Finally, Mrs. Peters can be considered the character most detached from the situation. As a sherrif's wife, she has surely adopted the mentality that "the man is in charge", as it is suggested from her actions in the story. She is shy, does not emit her opinions as firmly as Mrs. Hale, prefers to "stay out of it", and detours Mrs. Hale's opinions with sensible answers. However, there is a lot of Minnie Wright in Mrs. Peters; she also suppresses her emotions.
When Mrs.Peters tells the story about her kitten being bashed to death while she was being held back she admits to feeling the need to kill the person who did that to the kitten (she does not say the words "kill" but they are clearly hinted). Additionally, she commiserated with Minnie in that she, too, felt once alone and isolated without support after the loss of her child after moving to a new city. Mrs. Peters lets out a lot of herself toward the end of the play, demonstrating that she may too be living under the overwhelming figure of her husband.