Marilyn

Mariyln is one of the three Shadow Sirens and the middle sister of the older Beldam and the younger Vivian. If Beldam is the brains, Marilyn is definitely the brawn. She's is the strongest of the Shadow Sirens and is able to cast lightning magic against her enemies. She is described by Goombella as being the "strong, silent type". In fact, the only thing she seems to say is "Guh". However, she does say "The Three..." when the Shadow Sirens first meet Mario and company. Despite the usual grunting, her sisters can still understand what she is saying (or, at least, what she is trying to say).

After the Shadow Queen is defeated, Beldam and Marilyn give up on evil (as their queen has been destroyed once and for all) and make ammends with their sister Vivian.

Paper Mario 2 Stats
Boggly Woods Battle

HP 12, Attack 2, Defense 0 That's Marilyn. She's a Shadow Siren, Beldam's younger sister. She charges up her attacks occasionally. Says here she's the toughest of the sisters, so it might be best to defeat her first, huh?" Other than that, she doesn't have any particularly outstanding characteristics.

Palace of Shadow Battle

HP 40, Attack 7, Defense 0 That's Marilyn. She's Beldam's sister, another one of the Shadow Sirens. She'll attack you directly or use lightning. She also saves up energy for a big attack sometimes. So long as you avoid the brunt of her attacks, she shouldn't be too tough...