Lilia explains that Sebek is “known throughout Briar Valley for his gargantuan appetite,” and we receive several reminders throughout the game about how much he eats:
Sebek talks about having “only three extra servings at lunchtime” and both Silver and Deuce comment on him being a big eater (Silver calls him a bottomless pit).
He also has lines about needing “something with meat” and, to the prefect, he says that he is always hungry no matter how much he eats: “You and Grim are starting to look pretty appetizing, you know…”
As for why Sebek has this character train, he explains that his mother, “has some of the most potent occlusal force in our family–ah, that is, biting strength. It’s a Zigvolt trademark.”
While his father is a human, Sebek’s mother is “a creature of the night–that is, a nocturnal fae,” but there might be more to his lineage.
Floyd, Rook and Leona all refer to Sebek as a crocodile. This may be hinting that his family is a crocodile-based sort of nocturnal fae, much in the same way that Lilia seems to be based upon bats?
And crocodiles can’t chew, they can only swallow food whole.
And all of this may have something to do with why he says “I’ll swallow you whole” before battles! It is a literal translation of his original line :>
Bonus: Amazing artist Egophiliac has a comic about Sebek’s father meeting his mother, which ends in a drawing of a crocodile and one of those little birds that clean crocodile teeth, which a great theory for why Sebek’s father was made into a dentist.
Colloquially known as “crocodile birds,” they are also called “Egyptian plover” birds.
And “Sebek” (also called Sobek or Sobki) is an ancient Egyptian deity depicted with a crocodile head who was said to have eaten at least part of Osiris.
So it seems that ancient Egypt, crocodiles and eating people are all being woven into Sebek’s character, culminating in Sebek using “I’ll swallow you whole” as a battle cry.
Twisted Wonderland Reference Note 