After his sudden and violent test of his loyalty to Mrazivý, followed by the subsequent apology from her brother and sister who had set it up, Marcus sat back down, and put a hand on Mrazivý's shoulder.
He could tell she was a moment away from snapping, and while he could not blame her, now was not the time.
'At the first sign of trouble with my little sister, I shadowed her for two days in my ghost form, and investigated her friends, and took care of her biggest bully. I can understand where they are coming from, so try not to be too mad. Okay Mraz?' Marcus said to Mrazivý via his telepathy to try to calm her down a bit.
And luckily it seemed to have worked well, since she took a deep breath, before seriously looking at her brother and sister, and said, "I get why you did it, but please never do something like that again."
Having handled things calmly, Mrazivý surprised all of her siblings once again.