Jellaby: Monster in the City by Kean Soo

From chapters.ca:
As Portia, Jason, and Jellaby continue their journey through the city of Toronto, Portia is torn between her friendship with Jellaby and her duty to help the sweet monster find his way back to his home. How can Portia say goodbye forever, when Jellaby has become her best friend? But the clues leading them to Jellaby's origins begin to turn sinister. When a hooded wizard introduces them to another monster like Jellaby, Portia and her purple friend are in for a gruesome shock - this monster befriends children, too - and then she eats them! Now Portia must find a home for Jellaby, save Jason from the grasping tentacles of his new "best friend," and come to terms with the mysterious disappearance of her father. It's a lot to take on, but Portia is mad, bad, and ready to kick some monster butt.