1- He was born red
This was referenced at least a few times in this comic and the cast page: he was born red, but is prematurely "bluing", which is like how people's hair gets white when they grow old, except blobs get blue. Why? I have no idea. Maybe they regress to watery tones...
2- He can scale his mass and size up to factor 20
Metamorphs have a limit of how much mass they can "magically" create or destroy to achieve different sizes, and that amount can be enhanced with practice. In case of Jello, he can grow approximately 20 times in size... unfortunately, he isn't that big to begin with so...
3- He can grow limbs if needed
As demonstrated in the "Dinner at Stiffs" arc, and also a few times before(but I'm not sure anyone ever noticed that.) Thing is, growing parts of body requires some extra energy(it's a bit like tensing your muscles), so he just slides around when he doesn't really needs limbs.
Besides, being carried around by Flora beats walking by miles, man!
4- Part of his family is from the Manga Islands
The Manga Islands are a region beyond the Fourth Wall just like Webcomic World, and in rare cases some families migrate(though it's more common for immigrants to come from the Comix Megalopolis or Funnies Farms). But what really matters here is that I made a joke with anime eyes. Otakus, rejoice!
5- He still haven't got the hang of changing his face
Faces are tricky, they have this huge muscular density and very subtle movements to emulate.
About the Ditto... if you weren't a fan of Pokemon when the first season came out, you might not get this one. It sort of just came to me after I made the second fact's illustration.
6- He works in a daycare when he can't find work as a filler
Sometimes webcomics just don't need props and fillers, but they still need money, so they need to get some jobs somewhere else. In Jello's case, that surely beats chemical testing or parade float.
7- He is overweight.
He is just a little denser than the usual ball of goo, no big deal.
But, frankly, I couldn't miss the opportunity to use that excuse with someone who doesn't even have bones(but, incidentally, he has teeth. Freaky, huh?)
8- His biggest dream... To be able to live with a humanoid body 24/7!
Yes, he loves sliding around and being carried by his girlfriend, but sometimes you just need a big body of your own for activities such as driving, playing sport or dating(not many women appreciate the versatility of an amorphous metamorph!) But keeping a shape requires some huge amounts of training and energy. Keep reaching for that dream, Jello!
— Bruno "Professional Mole" GuedesFriday, September 10th 2010
9- He tastes like blackberries!