Yeah, I don't think the artist expected Mortis to be fully earnest with Soyo and say "Help me."

To be fair though, Mortis is herself a very interesting character. She essentially exists as a defense mechanism of Mutsumi and the stress she experiences in her day-to-day life, to the point of tagging in when it hits a breaking point, and Mortis essentially remembering for Mutsumi. Of course, with Ave Mujica disbanded, Mortis's entire reason for being, the purpose of her existence which practically gave her form and a name, is gone. And if she doesn't do something, Mutsumi will be gone too.