I'm not sure what color I should pick for Grimbald. The only color I know I don't want is scribble.

Sounds like a neat name for a graveyard colored Blob.

That had crossed my mind. A bit ironic for a pet named after a 9th century monk.

I tend to pick colors based on the pet's personality. Maybe try that way, if you have a story for him in mind?

No I don't really have anything in mind for him yet.

If you go for the monk idea, maybe aqua?

And darkmatter would be cool if you emphasize the "grim" aspect of the name :)