Silence is Erika's second-favorite unitmate after Intensity! Which maybe doesn't sound that exciting put that way, but it's important. I mentioned on plurk at some point, but Erika is actually much more endeared by standing up to her and arguing with her than by bending to her will or cowering. Erika's initial perception of the unit was strongly colored by the protection game which was just after they arrived, when basically no one was interested in having an opinion on strategy except Intensity and Erika had to do her best to make one up. IT WAS A LOW OPINION.

But especially around Maki-live time, Silence was actually trying to BE PROACTIVE and BUILD A STRATEGY and also listened to Erika explain why friendship was not going to save them and was logical about it, so Erika's opinion of her improved dramatically. She's still not sure Silence is... smart... or any particular challenge to her, which is why she ranks below Intensity, but she does at least like her personality-wise a bit more.

MEANWHILE... Erika does not care for Song at all. In either sense of that phrase. Erika already has a very negative opinion of alternate personalities for spoiler canon reasons, and then Song being nice and naive is just the nail in the coffin. Erika prefers to not think of her as a person at all. Hm.