I'm in awe of people able to manage more than one character. Seriously. I'm so spastic and easily distracted that it's impossible for me to do it. XP
If Cutter is a naturally quiet person, he'll get along just fine with Mocchi, even though I think Mocchi might find him a bit intimidating. Frankie's staring probably won't bother Mocchi so much--he's used to it, really. But his tattoos will probably be kind of fascinating to Mocchi. He might follow him around a little. >_>
As for Ella, she could probably coax Mocchi into anything with relative ease. He sort of likes peppy, chatty people. This could lead to shenanigans in the future and I approve so hard.
Aaah, the idea of Mocchi making balloon animals for Esther's daughter! Yes! :D